Bump vs Full Length Sizing

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ShifuXPrivate
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Bump vs Full Length Sizing
03/03/2015
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I understand the concepts. But can any FL die be used to bump?

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reloader112XFirst Sergeant
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Re: Bump vs Full Length Sizing
03/03/2015
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If you use a FL die to bump, you will also full length size the case. Just bumping the shoulders is over sold, just FL size and bump the shoulders back.

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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
03/03/2015
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[HR][/HR]No standard FL die on the market can bump the shoulder without first reducing it's diameter. Even Redding's body dies reduce the diameter of the shoulder and base. If you only wanna bump the shoulde you need to have a custom die made using your fireformed cases.
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HodgdonExtreme

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Re: Bump vs Full Length Sizing
03/03/2015 Last edited 03/03/2015 by HodgdonExtreme
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spawnof918v wrote: No standard FL die on the market can bump the shoulder without first reducing it's diameter. Even Redding's body dies reduce the diameter of the shoulder and base. If you only wanna bump the shoulde you need to have a custom die made using your fireformed cases.​
Forster makes what they call a "bushing bump" die, which only sizes the neck via bushing, and pushes the shoulder back. No body sizing performed.

Good kit, for certain purposes.

http://www.forsterproducts.com/store.asp?pid=36223
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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
03/03/2015
[HR][/HR]It still sizes the shoulder.
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HodgdonExtreme

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Re: Bump vs Full Length Sizing
03/03/2015
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spawnof918v wrote: It still sizes the shoulder.​
Yes, that's the point - it pushes the shoulder back, and sizes the neck per whichever bushing you choose.

It does not size the body.
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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
03/03/2015
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[HR][/HR]What is the shoulder diameter before and after the bumping operation?
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HodgdonExtreme

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Re: Bump vs Full Length Sizing
03/03/2015
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spawnof918v wrote: What is the shoulder diameter before and after the bumping operation?​
First, understand that few of us have the tools/instruments required to truly measure the diameter of the case body where it intersects the shoulder. You can get close with a caliper, and shimmy the caliper up the body until it's just about to pop off the body, but it is not a highly accurate/scientific way to get the measurement.

That said, I did my best and measured several cases fired in my CBI-barreled Savage 308 at .453 plus a cunthair or two. So maybe ~.4532ish, perhaps, though again I caution attempting to quote such exact numbers for such an inexact measuring method.

Anyway, after using my Forster bushing/bump die to achieve .001" bump (having been zeroed on the fired cases), I could detect zero difference in the body/shoulder junction diameter; they still measured ~.453 + a cunthair or so.

I do not stand corrected.
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ShifuXPrivate
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Re: Bump vs Full Length Sizing
03/03/2015 Last edited 03/03/2015 by Shifu
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reloader112 wrote:
If you use a FL die to bump, you will also full length size the case. Just bumping the shoulders is over sold, just FL size and bump the shoulders back.​
So when people talk about bumping the shoulders, they usually mean using a FL die to bump the shoulders back (and resize)? It seems no one mentions about using custom dies in the tutorials or youtube videos.

For using an FL to size and bump, does that mean adjusting the die so that it pushes the shoulder back 0.001 to 0.002" from a fireformed case? This will in fact resize the rest case as well?

I saw the forster bump neck sizing die, which can bump. But it seem that if you use it in bump mode (with no bushing), it is really like a FL die?



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HodgdonExtreme

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Re: Bump vs Full Length Sizing
03/03/2015 Last edited 03/03/2015 by HodgdonExtreme
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[HR][/HR]Yes, you've got the idea.

If you "bump" using an FLS die, you will be pinching down the body of the case a little. How much depends on the die you choose - ranging from ~zero with the aforementioned Forster bump die, to ~quite a bit using a small base die. A FLS die will be a little more than zero, and a "National Match" die will usually be a little more yet, but not as much as the smallbase. It'll also vary a little from one brand die to the next - and probably how early on in the die-reamers lifecycle it was used to cut the die.

All that said, I wouldn't overthink this.

Using a FLS die to bump shoulders back ~.001-.002" is what probably 95% of the shooters here do with great success.

There are probably reasons why uber-anal F class shooters and benchresters do things their own different way, but for a practical field rifle, the FLS die is the way to go.

If there is extra accuracy to be had by not sizing the body at ALL, it sure ain't much.
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ShifuXPrivate
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Re: Bump vs Full Length Sizing
03/04/2015
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Thanks HodgdonExtreme and everyone else.

This makes sense now. Since I'm starting reloading, I'll definitely use the FLS die and may consider playing with the Forster bump die.

How do you find out small base or measurements of dies? I haven't seen any specs or measurements of dies.

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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
03/04/2015
(1 vote)
[HR][/HR]Small base dies size the base .001" more than standard dies.
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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
03/04/2015
(3 votes)
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---------------------------------------------
--- HodgdonExtreme wrote:

spawnof918v wrote: What is the shoulder diameter before and after the bumping operation?​
First, understand that few of us have the tools/instruments required to truly measure the diameter of the case body where it intersects the shoulder. You can get close with a caliper, and shimmy the caliper up the body until it's just about to pop off the body, but it is not a highly accurate/scientific way to get the measurement.

That said, I did my best and measured several cases fired in my CBI-barreled Savage 308 at .453 plus a cunthair or two. So maybe ~.4532ish, perhaps, though again I caution attempting to quote such exact numbers for such an inexact measuring method.

Anyway, after using my Forster bushing/bump die to achieve .001" bump (having been zeroed on the fired cases), I could detect zero difference in the body/shoulder junction diameter; they still measured ~.453 + a cunthair or so.

I do not stand corrected.

---------------------------------------------

What happens when you bump more than .001"? Does the shoulder diameter increase?

What I'm getting at is that you can't push on one side of the case without affecting the other. You can't bump the shoulder without bowing the case walls. How do you deal with springback? Some cases spring back more than others? Some cases require more shoulder bump than others. How do you deal with all that?

By that definition a Lee collet neck die bumps the shoulder .001" as well.
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tucker301

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Re: Bump vs Full Length Sizing
03/04/2015 Last edited 03/04/2015 by tucker301
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I've been trying to understand bump sizing for a couple of weeks now, and what was just said is what I have not been able to resolve either.

If you move .001 here, it has to go somewhere.

That and I have no idea how to set a FL die to only engage the shoulder and leave the rest of the case alone.



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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
03/04/2015
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[HR][/HR]You can't.

The only way to do this is to get a custom die made using specs off your fireformed cases. The wsy a FL die works is the body and shoulder get reduced in diameter first and this pops the shoulder forward. As the die finishes sizing the neck it finally contacts the shoulder and bumps it back which swages some of it into the neck. And so the case grows in length.
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drjjlXSergeant
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Re: Bump vs Full Length Sizing
03/06/2015
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---------------------------------------------
--- spawnof918v wrote:

You can't.

The only way to do this is to get a custom die made using specs off your fireformed cases. The wsy a FL die works is the body and shoulder get reduced in diameter first and this pops the shoulder forward. As the die finishes sizing the neck it finally contacts the shoulder and bumps it back which swages some of it into the neck. And so the case grows in length.

---------------------------------------------

This. When I was first learning (still learning) and setting up my FL dies, I noticed that at first my base to shoulder measurement actually got LONGER...screwed the die in little by little until the shoulder finally got bumped back .002 from fired brass measurement. The brass gets squeezed and pushed and has to go somewhere.
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goodgorillaXSergeant
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Re: Bump vs Full Length Sizing
03/08/2015 Last edited 03/08/2015 by goodgorilla
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How far back should I keep the shoulder? Should I bump it back .002 from a once fired case or bump it back to virgin brass length?

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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
03/08/2015
(1 vote)
[HR][/HR].002" for bolt gun, .004" for semiautos.
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ZenBiker990

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Re: Bump vs Full Length Sizing
03/11/2015
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[HR][/HR]I've done both. For me, neck sizing was more of a problem than a solution, especially if the chamber is not perfect and you don't index your cartridges. My recommendation is to buy the best full length sizing dies you can buy. i.e. Redding; use bushing dies if you want to go that route ( I personally don't ), then buy a headspace gauge so you can set your sizing die to bump the shoulder back between 0.001-0.002". I've used several brands and configurations of gauges, but I just got the one designed by Larry Willis/innovative Technologies (larrywillis.com) and have found it to be the best, easiest to use, and most accurate. For $100 it handles any cartridge and uses a digital readout gauge; beats the hell out of squinting at those tiny numbers on dial indicators. FWIW, I recommend FL sizing with minimum shoulder "bump" over neck sizing.
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HHarkeX376 MONTHS
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Re: Bump vs Full Length Sizing
03/19/2015
[HR][/HR]You can have a custom honed FL bushing die made from a Redding Body die and 5-10 fired cases for $80

Jim Carstenson at JLC Precision will take a Redding Body die and 10 cases fired 3x and hone the body die to perfectly FL size your brass AND convert it to bushings with a deprimer that does not use an expander ball

One of the best deals you can find to increase your accuracy. Just google JLC precision. Take about 2-3 weeks normally
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OpxnvXCorporal
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Re: Bump vs Full Length Sizing
03/29/2015 Last edited 03/29/2015 by Opxnv
[HR][/HR]That sounds like a pretty good deal. How much did you see on the target?

I use a Redding FL with bushings to control neck tension. I set the die up so that the bolt handle (sans firing pin group and ejector pin) drops roughly halfway (or 2/3 of the way) then I can close it the rest of the way with 1 finger. Even if the gun gets dirty I can still close the bolt. I have good chambers so the alignment is right.

For one of my guns a custom fit die would be good. The 308s were mostly cut with different reamers so, for me, there isn't much point.
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6mmcreedmoorXFirst Sergeant
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Re: Bump vs Full Length Sizing
04/12/2015
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HodgdonExtreme wrote:
spawnof918v wrote: No standard FL die on the market can bump the shoulder without first reducing it's diameter. Even Redding's body dies reduce the diameter of the shoulder and base. If you only wanna bump the shoulde you need to have a custom die made using your fireformed cases.​
Forster makes what they call a "bushing bump" die, which only sizes the neck via bushing, and pushes the shoulder back. No body sizing performed.

Good kit, for certain purposes.

http://www.forsterproducts.com/store.asp?pid=36223
My Hornady 6 Creed custom NS only bushing die bumps the shoulder, have another which sizes the body and bumps the shoulder.​


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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
04/18/2015
(2 votes)
[HR][/HR]Whenever you bump the shoulder, the body expands. The die has to size the body to some extent, otherwise the round won't chamber.
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SHahhshootXGunny Sergeant
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Re: Bump vs Full Length Sizing
04/20/2015
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HodgdonExtreme wrote:

That said, I did my best and measured several cases fired in my CBI-barreled Savage 308 at .453 plus a cunthair or two.​
Was this a standard cunthair or a red cunthair? As I'm sure you well-know, the red cunthair is the finest unit of measurement within the industry at this time. Just wanted to clarify for those who may have a RCH indicator and not the ICH.

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mkollman74XFirst Sergeant
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Re: Bump vs Full Length Sizing
04/30/2015
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[HR][/HR]Just FL size and be done. I FL size all of my brass everytime I load. Doesn't seem to affect accuracy a bit in my 6 Creed or .308. of course, I am the laziest reloader around. I do as little as possible to get the accuracy I need. I've found much of the brass prep voodoo isn't required at all. YMMV.
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ThebellyXGunny Sergeant
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Re: Bump vs Full Length Sizing
05/04/2015
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mkollman74 wrote: Just FL size and be done. I FL size all of my brass everytime I load. Doesn't seem to affect accuracy a bit in my 6 Creed or .308. of course, I am the laziest reloader around. I do as little as possible to get the accuracy I need. I've found much of the brass prep voodoo isn't required at all. YMMV.​
I recently had a struggle with FL vs. Bump only sizing of the brass body. To make a long story short: I tried to get fancy with it, and I ended up with a lot of frustration over the whole thing.

If you plan on using your rifle in a field-like environment, just set up your FL sizing die to bump the shoulders back and be done with it.
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A1J04

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Re: Bump vs Full Length Sizing
05/13/2015 Last edited 05/14/2015 by A1J04
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This has been entertaining as hell. lmao. We've all been there and over thought this, for ions. We're some crazy little monkeys who just like to make stuff hard on ourselves.

Ya, just slam the Full Length Sizing Die in the press, screw it down till it makes contact with shell holder and then back it off a few turns. Place a "FIRE FORMED" case with it's neck and shoulder either blackened with a sharpy or smoke it with a candle into the shell holder, run it all the way up and see if the markings are say around half way down the neck. Turn it down a tad more and do it again till you've sized the neck and touched/bumped the shoulder back .002 bolt/.004 other. You'll drive yourself crazy if you try to figure too much of this out at one time, especially when you think you're making your case shorter but it's GROWING ha.

Too much fun.

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ZmechanicXPrivate
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Re: Bump vs Full Length Sizing
05/29/2015
[HR][/HR]I went through the same thing. Before I bought a headspace comparator for my rounds, I set the sizing by using the stripped bolt and chambering the brass and checking the "fit" in the chamber. I don't advise this, it nearly drove me insane.

I will say, if you run your brass through a FL sizer, but don't let it also touch the shoulder, the headspace will most likely INCREASE. This has been my experience, anyway. Thinking about it, it makes sense. If the FL sizer shrinks the body of case any, where is that going to go? It's going to make it longer. I have had more than one person tell me to just "back the FL sizer out" if I don't want to bump the shoulder. After experiencing the headspace increasing, I quickly disregarded that "advice". I also don't like FL sizing without bottoming out the die on the shellplate. My rationale is that if you don't, then the shoulder bump amount becomes dependant on press rigidity and brass hardness. That would be a YMMV kind of thing, and I know I probably have one of the least rigid press setups around. In any case, I prefer to eliminate as many variables as possible. I would advise that if you want to control the headspace with a FL sizer, adjustable shell plates are the way to go.

I've also heard people say to take the de-capper/expander out of their FL sizer. I've never seen how that would be a benefit, at least with the FL sizers I've seen. Most of them shrink the neck a decent amount under what it needs to be, then rely on the expander to, well, expand it back out. If you take that out, your neck tension would be ludicrous. The option there is a bushing die, or a custom honed FL sizer.

Also, don't always believe the equipment. I had a LEE shell plate that was almost 0.002" too shallow. If I let the die bottom out on it, it would actually produce cases that were below the min headspace on my case gauge. Not cool.
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bigedp51XGunny Sergeant
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Re: Bump vs Full Length Sizing
06/24/2015 Last edited 10/28/2015 by bigedp51
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Shifu wrote:
I understand the concepts. But can any FL die be used to bump?​
We live in a plus and minus manufacturing world and no two dies and chambers are exactly the same. I have a Lee .223 full length resizing die that pushes the shoulder back .009 shorter than a GO gauge and .011 shorter than the chamber headspace. It also sizes the base of the case smaller in diameter than two small base dies I have.



In the illustration below is the exaggerated effects of full length resizing, pay close attention to the blue, red and green dotted lines and the word shoulder setback
 
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The more you push the shoulder back from its fired length the "MORE" head clearance you create with your reloaded cartridge. And the more room you give the case to thin and stretch in the base web area when fired, which causes case head separations.







If you have too much head clearance when fired the brass will exceed its elastic limits and stretch and thin in the base web area.







Below is a fired unresized .223/5.65 case in my Hornady cartridge case headspace gauge.







Below the same case after full length resizing with .003 shoulder bump. (shoulder setback)







Below on the left is the Redding competition shell holder used on the case above, this shell holder where the base of the case rests is .004 "LOWER" than the standard RCBS shell holder on the right. And with the Redding shell holder the press still reaches cam over, and if the RCBS shell holder on the right had been used with the press reaching cam over, the shoulder of the case would have been pushed back .007.







Bottom line, your dies are threaded and can move up and down and can be adjusted for the correct amount of shoulder setback for "YOUR" rifle.

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dondlhmn

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Re: Bump vs Full Length Sizing
07/02/2015 Last edited 07/03/2015 by dondlhmn
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This is an interesting discussion. I have a couple of 6.5 Creedmoor rifles that have different dimensioned (but only BARELY) chambers.. Rifle" A" has a sort of "tight"chamber. Cases fired in that rifle don't get expanded as much s the cases in rifle "B", which has a slightly (but still within correct tolerances) larger chamber. Brass fired in Rifle "B" will not go into the chamber of rifle "A" and allow the bolt to be closed on it without a good bit of grunting, but a piece of brass fired in rifle "A" will go into the chamber on "B" with no problems at all. Even now part of my cure for all this is to keep the brass used in these two rifles, even though it is the same brand and caliber and number of firings, separate, which is no big deal since I tend to keep brass separate for each rifle I have, anyway. The rifle with the tighter chamber will, after the brass has been neck sized only for several firings, it will (as is pretty normal behavior for baras) expand to the point where it will be difficult to get the bolt to close. I tend to check neck lengths (and brass trim length) pretty carefully after neck sizing and trim as necessary. BUT, what happens is that the case gets harder and harder to chamber and then impossible.....I thought that the case was growing in length might have something to do with this problem (maybe a little too much headspace?), resulting in the shoulder being too far forward and giving me the hard bolt closing. So, I tried running those cases through a FL sizing die (actually tried THREE DIFFERENT BRANDS of DIES). After doing that the brass was still a hard fit...bolt closing was tough....so I started doing some checking of case dimensions in all directions and discovered that even though the case was FL sized, the area about .200" ahead of the ejector groove and just ahead of the "web" was showing signs of interference (I used Dykem on the brass to show where it was making contact) so, after FL resizing and finding that the cases were still tight in the chamber, I stuck one in a collet chuck in my lathe and started shaving a couple of TEN THOUSANDS of an inch at a time off of the part of the case showing the contact and then trying it in the chamber. After shaving off a little a couple of times and still not having the bolt want to close, I suddenly found that the bolt closed and the brass showed no signs of interference, hard contact or anything else. Along the way I thought that maybe I was having a pressure problem, but the cases showed no signs of stretch or getting thin anywhere....SO...I got hold of a small base resizing die and ran the cases for rifle "A" through that about every 3rd or 4th loading and just neck sized the rest of the time. Problem solved....it turns out that the chamber in rifle "a" is a few ten thousandths (like 3 or 4) tighter than the usual spec for that cartridge so Fl resizing just wasn't taking them down far enough by about 3 or 4 TEN thousandths. So now I NEVER SB resize for Rifle "B" and only do an occasional FL sizing while doing only the neck sizing most of the time, but occasionally SB the brass for Rifle "A". Both brass life and accuracy remain great with both rifles and I think I am doing the right thing.....!?!?!?!?

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spawnof918vXFirst Sergeant
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Re: Bump vs Full Length Sizing
07/18/2015
(1 vote)
[HR][/HR]SB resizing does not affect accuracy or case life. I SBFL size for everything, taking care to bump the shoulder minimally. I am fortunate my semi-auto chamber is within .001" of my bolt gun chamber in terms of headspace. But a FC case sized that way will last in excess of 20 firings with moderate (50KPSI) loads.
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ZenBiker990

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Re: Bump vs Full Length Sizing
08/12/2015
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A1J04 wrote:

This has been entertaining as hell. lmao. We've all been there and over thought this, for ions. We're some crazy little monkeys who just like to make stuff hard on ourselves.

Ya, just slam the Full Length Sizing Die in the press, screw it down till it makes contact with shell holder and then back it off a few turns. Place a "FIRE FORMED" case with it's neck and shoulder either blackened with a sharpy or smoke it with a candle into the shell holder, run it all the way up and see if the markings are say around half way down the neck. Turn it down a tad more and do it again till you've sized the neck and touched/bumped the shoulder back .002 bolt/.004 other. You'll drive yourself crazy if you try to figure too much of this out at one time, especially when you think you're making your case shorter but it's GROWING ha.

Too much fun.​
The force is strong with this one. Wise, he is.

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SH10FPXPrivate
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Re: Bump vs Full Length Sizing
08/14/2015
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I am relatively new to reloading but not a full novice. This thread is interesting to me as I had problems with resizing for my Savage 223 and 308. Fireformed brass for both would not rechamber. I find that I can resize the brass to the size that will fall in and out of a Lyman case gauge, but still not chamber. I must tweak my RCBS FL sizing die down gradually until the case will chamber easily. When I'm doing this final tweaking, am I bumping the neck or sizing the base? I see that FL sizing is a must for my chambers. I intend to buy Redding or Forster dies, so I'm hoping it will streamline the process.

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morganlamprechtXFirst Sergeant
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Re: Bump vs Full Length Sizing
08/14/2015
[HR][/HR]when you use a FL die, it squeezes the body, pushing the shoulder forward before you ever hit the case shoulder with the die...if your die isnt turned in far enough to push the shoulder back after its pushed forward, the brass isnt likely to chamber...if you only neck sized (with a neck die) this wouldnt happen as a neck die doesnt squeeze the case body at all...i have neck sized, but prefer to use FL/neck bushing dies because they feed smoother...i really like the redding type s fl bushing dies and they give great results
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SH10FPXPrivate
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Re: Bump vs Full Length Sizing
08/14/2015
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That makes sense. I was concerned that I was bumping the shoulder too much when trying to size enough to chamber easily. I think I'll go with the Redding type S dies. Heard nothing but good things. Thanks for the feedback.

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Tuxedo007XPrivate
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Re: Bump vs Full Length Sizing
08/17/2015
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I would be very watchful for incipient case head separation! With case head separations, they can range from mild to wild! While it appears that in some cases the attempt is to separate the fly crap from the black pepper, there IS a lot to be gained by correct case resizing. Just throwing the same cases into the Full Length die & sizing away can lead to problems if repeated often enough!

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Tuxedo007XPrivate
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Re: Bump vs Full Length Sizing
08/17/2015
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ZenBiker990 wrote:
A1J04 wrote:

This has been entertaining as hell. lmao. We've all been there and over thought this, for ions. We're some crazy little monkeys who just like to make stuff hard on ourselves.

Ya, just slam the Full Length Sizing Die in the press, screw it down till it makes contact with shell holder and then back it off a few turns. Place a "FIRE FORMED" case with it's neck and shoulder either blackened with a sharpy or smoke it with a candle into the shell holder, run it all the way up and see if the markings are say around half way down the neck. Turn it down a tad more and do it again till you've sized the neck and touched/bumped the shoulder back .002 bolt/.004 other. You'll drive yourself crazy if you try to figure too much of this out at one time, especially when you think you're making your case shorter but it's GROWING ha.

Too much fun.​
The force is strong with this one. Wise, he is.



Amen!​


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NameEnoughXGunny Sergeant
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Re: Bump vs Full Length Sizing
08/17/2015
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Tried bump neck sizing and it's not for me.

I shoot F-TR class and full length size. Most of the F-class shooters I converse with also full length size to get a consistent case.

Of course I also do other things - I anneal each time I reload. I know guys that anneal before and after processing. I also turn necks and trim each reload every time. I also check concentricity each time and I use a 309 expander mandrill to reduce neck tension. So I am not shy of doing a little extra work.

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lrgrendelXSergeant
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Re: Bump vs Full Length Sizing
08/17/2015
[HR][/HR]New 6.5 Creedmoor bolt gun.

Using Hornady brass, hoping to get 5 or 6 reloadings.

Would love one of those Forster should bump/ bushing dies but it is not made in this caliber.

Don't want to over work the brass????

What are my choices?? Don't mean to take over the thread.....
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ArmyJerryXFirst Sergeant
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Re: Bump vs Full Length Sizing
08/30/2015
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Get the lee collet die and a set of whidden dies, non bushing. You should get a hornady headspace gauge set to measure the before and after sizing to make sure you are not over sizing. FYI you will get loose pockets before you get case head seperation with the 6.5 creedmoor Horn brass.

lrgrendel wrote: New 6.5 Creedmoor bolt gun.
Using Hornady brass, hoping to get 5 or 6 reloadings.

Would love one of those Forster should bump/ bushing dies but it is not made in this caliber.

Don't want to over work the brass????

What are my choices?? Don't mean to take over the thread.....​
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bigedp51XGunny Sergeant
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Re: Bump vs Full Length Sizing
09/03/2015
(3 votes)
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Shifu wrote:
I understand the concepts. But can any FL die be used to bump?​
Any full length die can be used to "bump" the case shoulder and "bump" is just a word. The term bump refers to minimal shoulder setback when resizing and not setting your full length die as per the instructions. I have a Lee .223 full length die that will bump, shove, push the shoulder back .011 shorter than my chamber headspace if the die makes hard contact with the shell holder and the press cams over.

Below, "bump" for a bolt action would be .001 to .002 below the red dotted line. And if you set the die up per the instructions and having the press cam over the shoulder would be at the green dotted line. Bump is a word used to explain "minimum" shoulder set back.





My neck sizing bushing die below "bumps" the shoulder when needed and does not touch the body of the case.







Below is a .303 British case forming and trim die with a fired case inside the die, the body and neck of the case are not touching the inside of the die. And my little finger is keeping the case from falling out of the die. And by adjusting this case forming die up or down I can "bump" only the shoulders of my fired cases when they become hard to chamber when neck sizing only. The case forming dies are used to form cases and the inside of the die is approximately .010 larger in diameter than the standard die, and why it does not size the body of a fired case.







And if after reading this if we meet on the street we could say we "bumped" into each other. But if I hit you with my car in the street I would push your shoulder back as far as it would go. And that would be the green dotted line the medical examiner would put on your over worked compressed shoulder.

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HHarkeX376 MONTHS
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Re: Bump vs Full Length Sizing
09/09/2015
[HR][/HR]two points

1. You can use one set of dies without changing the settings/lock ring for two or more guns with different headspace by buying a set of Skip Otto shims from Sinclair internation ($13) and headspacing the die on the shortest case and using the appropriate shims for the longer cases. They just go under the die and are from .001 to .010. cheap, accurate and work great for multiple guns and one set of dies.

2. Several commented that IF you set the die flush with the shellholder to get cam over you can push back the shoulders quite a bit. I have seen .015. You can push back to the point that the case will not chamber as it pushes the side of the shoulder/case joint out too much. I have seen this happen on three occasions. Just back the die off as mentioned and come down 1/4 turn until you get the .002 shoulder bump you are looking for.
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XringerXPrivate
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Re: Bump vs Full Length Sizing
09/29/2015
(1 vote)
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I'm going to have to disagree with the "Full Size and go" option. I own the Forster Neck/Bump die, and I can tell you from experience that you will get many more loads from your cases if you neck/bump as opposed to FL resizing. That's not to say you should never FL size. As a rule of thumb, I will FL resize every 5th load. This pic is a perfect example of case head separation. Remember, it's very important to clean then inspect cases BEFORE reloading them. There is such a thing as overworking your brass. Each time you size it it becomes invariably weaker. There is another way to check for early separation using the "coat hanger" method. Take pliers and turn a 90 on the end that small enough to fit in the case. Run the edge of the coat hanger up the side of the case from the bottom. If you feel an indention in the head of the case a few mils up the wall, discard the case and move to the next one. It's true that 308 cases can be fired well into the double digits. but I also have WSSM cases that have reached double digits as well. Tis better to be too critical of spent cases than have a head separate in the field.


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okiefiredXFirst Sergeant
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Re: Bump vs Full Length Sizing
10/27/2015
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I'm with Xringer. I've used the bump/bushing die for years with great results. Keep track of your brass and use it in the same BA rifle and no need to FL resize. If you do, you're working the brass for no reason. That said, I FL size everything for auto loaders but to be honest, don't know if it's always needed. For precision, case prep is a must, i use Lapua and Norma for that, it's about consistency. Something I haven't seen mentioned in this thread is neck turning....which helps ensure proper tension, concentricity and feeding. True it's not complicated but like everything, consistency in ammo takes more time and better quality equipment.

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Elfster4321

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Re: Bump vs Full Length Sizing
11/03/2015
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I just full length resize with a shoulder bump. Easy and accurate for me... Using Redding national match 3die sets

.001 to .002 for bolts
.003 to .005 for semi autos

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JigStick

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Re: Bump vs Full Length Sizing
11/06/2015 Last edited 11/06/2015 by JigStick
[HR][/HR]I learned to reload by some top notch short range bench rest shooters. When it comes to hunting and tactical guns they always full length size. Having the cases reliably chamber is what is most important. FL sizing and bumping the shoulder .001-.003 for a hunting or tactical rifle is not going to make a difference when it comes to accuracy, precision, or case life. What it has the potential to do is cause a round not to chamber at the worst time ever. The idea that it will extend case life is a myth. You are still working the brass.

Now. Do I FL size and bump shoulders in my hunting rifles? Sometimes. Depends on what and where Im hunting. For western PA deer hunting I will. Because Im 100% certain Ill be needing only 1 shot. usually I only put 1 in the gun. And If I'm using one of my BAT single shot actions even more so. And why do I do it? Because I set up my dies the first time I used them to accomplish that. Using "Skips Die Shims" from SinClair Int. Thats the only reason.

When I'm hunting black bear with a BAT or Stiller repeater in 10ft tall mountain laurel, hell no. Ill FL size and bump that shoulder back all the way. Not worth the risk of not having one chamber because I tried to get cute reloading and keep SB to a minimum. A wounded or charging blackbear may require a quick follow up. Worst time for a round not to chamber.

Now when Im with my buddys at bench rest matches, or shooting 6BR's and 6PPCs, hell yeah. I want that case snug and tight in the chamber. When you're shooting bugholes like that it may make a noticeable difference in group size.
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okiefiredXFirst Sergeant
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Re: Bump vs Full Length Sizing
11/08/2015
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It's true, all sizing dies "work" brass. Bench rest shooter or not, to insinuate they all work it the same way or as aggressively is just plain wrong. it's common scence, why work it more than need be? In 30+ years of reloading, I've never had a round I couldn't chamber sized by a bump/neck sizing die in the rifle it was reloaded for. Everyone knows bench rest shooters and they're just like the rest of us, they all have opinions just like they all have ass..... ;) Very few opinions trump personal experience with me.

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VooDoo62XPrivate
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Re: Bump vs Full Length Sizing
11/21/2015
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Is it possible to have a bolt rifle chamber that is so tight in tolerance that you have to FL size every time you reload the fired cases? I neck size the cases for my .308 and they are tight in the chamber they were fired from once reloaded. New rifle for me, I have never had this problem before. The cases are fully prepped and polished, trimmed, deburred, chamfured, etc. The case alone fits fine but when a bullet is seated it gets hard to close the bolt no matter what depth the bullet is seated at. The outside of the case will have scrubbing marks on it when removed from the chamber when trying the ammo for size.

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5RWill

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Re: Bump vs Full Length Sizing
12/07/2015
[HR][/HR]
I declare this thread resurrected! Hehe



Anyhow so which does everyone use? For your field rifles i.e. match/hunting do you all FL resize for reliability? I'm thinking about giving a forster bump die a shot to try and conserve brass life maybe tighten the groups up a tad.

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gunman40XPrivate
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Re: Bump vs Full Length Sizing
12/07/2015
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anyone ever trie the RCBS "X" die? I know it's supposed to stop the case from lengthening, but does it full length size?

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Nightforce123X19 MONTHS
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Re: Bump vs Full Length Sizing
12/07/2015
[HR][/HR]For my 7mm08 I use a lee collet die to neck size, a Redding body die to size the body and push the shoulders back .002. I use a rcbs headspace gage to check how far I pushed the shoulders back. I use this all in a Forster co-ax press. It makes for very accurate and straight rounds.
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MikehotelXSergeant
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Re: Bump vs Full Length Sizing
12/18/2015
[HR][/HR]thanks guys,,

this discussion answers questions I asked in another thread...
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honesthopX23 MONTHS
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Re: Bump vs Full Length Sizing
01/06/2016
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I resolved much brass attrition, poor consistency in OAL, some accuracy issues, mostly vertical stringing, and headspace differences by learning proper case annealing. that brass has gotta go somewhere when we move it, as it gets harder. my $.02 on 'just screw the die in to the shell holder and FLS. the whole point of checking headspace is to gain accuracy improvement and case life. getting new brass where it fits takes at least 2 fireforms ,to me anyways, and just FLS 'all the way', even annealed brass will prematurely fail when numerous firings with long headspace and continued FLS all the way over and over WILL minimize case life. of my many different cartridges, 17's to .458, some I will anneal every 2 firings, others 5-6. I don't like tossing fully prepared brass away. my Swift brass goes 20 firings plus from care. the swift was designed as a dragster and that's me. it took me awhile to say 'self, you now understand headspace and it's related issues'. do I tho ? when shoulder below neck is against the same shoulder inside the firing chamber, the case head [primer end] should be ideally .002''-003'' from bolts face and walls. that is headspace. when the cartridge fires, it expands and seizes the chamber walls with 50,000 #'s of internal pressure or more. the brass expands lengthwise also so that .002''-.003'' clearance is gone to 0. bullet leaves, pressure is released, brass will spring back .002'' or so. custom chamber/dies can be 'matched' with custom clearance's, only neck sizing is done for many, many shots and bumped back when needed. some brass is fired up to 200 time with very minimal brass working done. I definitely believe controlled headspace clearances are worth it. every little bit helps to your goal.

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Tristian19

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Re: Bump vs Full Length Sizing
01/19/2016
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Before I went with BODY and NECK dies I successfully used FL Die to BUMP, as well as, FL Size case.

FWIW: I use Redding Dies.

Safe shooting...





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SigSavageXPrivate
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Re: Bump vs Full Length Sizing
01/26/2016
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I am brand new to reloading and this whole "sizing" thing has had me stumped. This thread has been very helpful, especially the pictures to hel me visualize what is going on in the sizing process. I have just been following the directions that came with my dies for set up (turn die down until it touches shell holder then back off a little bit), putting the brass in, and then pulling the lever down. I had an idea what the process was doing, but didn't fully understand all the different pieces of the process.

So, I'd like to please clarify a couple things so that I will do the correct process in the future:

1) get a headspace gauge. This will tell me the length of my chamber is by measuring the fired, unsized cartridge to within about .003" due to spring back. A once fired "new" piece of brass should've be use for this.

2) get a neck sizing die to just reform the neck of the case only so I can get the bullet in for seating. Neck sizing increases cartridge life.

3) every fifth reloading of a case, use my full length sizing die.

4) use a blowtorch and anneal the cartridge neck every fifth reloading. Do this before sizing.



Now, how do I use the info I get from the headspace gauge? When do I know if my cartridge needs to have its shoulder bumped back? Do I just go by the general feel of when I chamber the cartridge before shooting? If it is difficult to chamber do I assume it is because the shoulder is too far forward? Do I then measure the length of that cartridge using my headspace gauge? If it is too long then I need to bump the shoulder?

Also, when using the headspace gauge is it safe to assume that the brass measurement is an accurate representation of the gun's actual headspace as long as the cartridge can be chambered easily? Do I need to also do this test I've read about people removing the firing pin from their bolt and letting it fall into place, and if it goes 2/3 of the way on its own then the cartridge is the correct size?

Last, when it comes time to bump the shoulder back, how do I know how much more to screw the die down? Once it hits the shell holder and cannot go any further and it is not bumping the shoulder, what then? Or is this actually an issue? Do FL dies generally over-bump the case, requiring a person to actually back off the die and screw it out? If you are doing this, how do you know how much to back it off? Is it by ill and error using multiple cases?



thanks for any help.

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Tristian19

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Re: Bump vs Full Length Sizing
01/28/2016 Last edited 01/28/2016 by Tristian19
[HR][/HR]
I am FAR from a reloading expert so take anything I convey with a grain of salt. With that said:

1) Following link is to one of my head space gauges: Feel free to view product overview: midwayusa.com/product/727107/le-wilson-case-length-headspace-gage-338-lapua-magnum

2) I FL or BS size all my cases and not just NS << Not saying NS will not be sufficient for your caliber/situation

3) See #2

4) I would Anneal every one or two (Just me). Yes, anneal BEFORE sizing



When do I know if my cartridge needs to have its shoulder bumped back?

A: Depending on caliber I bump 0.001 to 0.003 evertime

If it is difficult to chamber do I assume it is because the shoulder is too far forward?

A: Definitely can be ONE sign

Do I then measure the length of that cartridge using my headspace gauge?

A: I would suggest you consider running ALL your cases through gauge every time, at least UNTIL you find it is no longer needed

If it is too long then I need to bump the shoulder?

A: Always use HS Gauge properly to rule out

Also, when using the headspace gauge is it safe to assume that the brass measurement is an accurate representation of the gun's actual headspace as long as the cartridge can be chambered easily?

A: Not qualified to answer. I also would NOT assume anything

Do I need to also do this test I've read about people removing the firing pin from their bolt and letting it fall into place, and if it goes 2/3 of the way on its own then the cartridge is the correct size?

A: Not familiar with this method as described

Last, when it comes time to bump the shoulder back, how do I know how much more to screw the die down?

A: Call Die maker and confirm how they suggest

Once it hits the shell holder and cannot go any further and it is not bumping the shoulder, what then?

A: Call Die maker and confirm how they suggest

Or is this actually an issue?

A: Cannot answer with certainty

Do FL dies generally over-bump the case, requiring a person to actually back off the die and screw it out?

A: Yes, IF performed incorrectly

If you are doing this, how do you know how much to back it off?

A: I measure, bump down and make sure brass has NO issues when I close bolt

Is it by ill and error using multiple cases?

A: I ONLY use same case manufacturer per rig (If you are referring to using different manufacturers) NOT saying you cannot



Do not take following negative, do some more research as answers are available. A lot of above is trial and error as well.

NOTE: Above are my thoughts and am NOT trying to say my way is BEST way. What I do works for me as my results display consistent 0.5 MOA prints. Simply sharing and possibly help out as that is what I thought SH is here for

Safe shooting...







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BuzzBoss915

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Re: Bump vs Full Length Sizing
01/29/2016
[HR][/HR]
Shifu wrote:
I understand the concepts. But can any FL die be used to bump?​
I think the answer is yes?

You may understand the concepts, but what really matters is your motive, or objective. Everyone has a theory, but you will draw your own conclusions based on exactly how anal you become. Bumping the shoulder is a very satisfactory resizing method, once you get the hang of it. What you should look for, (on an assembled round) is a slight resistance closing the bolt. BB

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honesthopX23 MONTHS
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Re: Bump vs Full Length Sizing
03/11/2016
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spawno1815v- instead of buying an expensive bump custom bump die, if an acceptable chamber die has the same shoulder angle [std chambering for a gunshow used die set for $20 or so]. buy it, cut it off to close correct length, flare a little for brass entry protection, and presto, a head space bump die less the body size aspect that ends there. if a lathe is handy, part it off, trim it to proper length. if you have chamber reamer, make your own bump die from 1144 stress-proof, or 12L, H20 quench. either are very simple to harden a little for great longevity. I hope I got that right. make sure of a good finish tho. I like bumpers for THE chambering being bumped. I have used 1018, in a salt brine solution. surface hardened a cat can't scratch. you just have to have the nice finish and heat treatment ss wrap,. the el cheapo method. [I've made 100's of brine hardened do-dads from mild hot rolled steel for many repairs from that method. had a Wyoming rig welder working for me on a turnaround that made really nice spurs, belts, quirks, etc., cowboy stuff. cheapest quirks he had were $700, 20 years ago spurs $2,000 . he had a PILE of hot rolled rawls[?] some buddy he had at IR cut 'em on their water jet. he'd file mark 'em so they'd looked old and brine harden to ring like clint eastwood walking down the boardwalks. just plain cool and a very useful learning info. table salt in water.--good luck!

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RwnielsenXPrivate
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Re: Bump vs Full Length Sizing
06/10/2016
[HR][/HR]
lrgrendel wrote: New 6.5 Creedmoor bolt gun.

Using Hornady brass, hoping to get 5 or 6 reloadings.

Would love one of those Forster should bump/ bushing dies but it is not made in this caliber.

Don't want to over work the brass????

What are my choices?? Don't mean to take over the thread.....
I have a Forster 6.5 Creedmoor bump- neck die. Got it at Natchez I believe, along with a Wilson case gauge​
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waynemacXSergeant
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Re: Bump vs Full Length Sizing
08/17/2016
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I use mostly Redding full length bushing dies and have good success with them. As has been mentioned, when you size and bump your shoulder, the brass gets displaced. That's why you have to trim brass from time to time. The question a bout brass spring back... As brass work hardens, think fire / size, fire / size, it gets harder and will spring back when you size. The solution is to anneal your brass. This helps with consistent bullet pull as well as keeping your sizing consistent.
And for the record, you ALWAYS full length size your brass. Neck sizing has no place when shooting a repeater, heck I full length size all my benchrest cartridges as well. Also, just a heads up, Hornady makes a nice custom bushing die that uses Redding and Wilson bushings. I have one of these for my .220 Beggs.
Wayne
 
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#7
I just want to know why you have two 6.5 Creedmoors! :)
If the brass doesn't chamber then you have to size it correctly.
If the regular f/l die doesn't do it, but the small base does, you've solved your problem. Congrats!

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May 6, 2017
71
1
8
#8
I'd just full length size. Never messed with shoulder bump and I've got pretty good results out of full length sizing
 
Apr 28, 2017
23
1
3
#9
I use the Redding precision shell holders. They come in a set of 5 or 6 and in various heights. Use the right one so you resize the least but the brass still fits your chamber. They're expensive but I don't like the crap about backing out the die, etc. Just not as repeatable. For my 6.5 Streetcred bolt rifle I use the +.010 holder - So it adds 10 thou to the headspace.
 
Likes: vitalemj
Oct 7, 2003
231
1
18
65
Fredericksburg, VA
#10
IF you want a custom fit and die that properly sizes then there is a way to get it without going expensive custom. Jim Carstenson at JLC Precision 563-212-2984 will make one out of a Redding body die.

You need to send him 10 cases fired 3x with full power loads. He will custom hone the body die to size for your chamber, convert the body die to bushings also so you can control the necks. Last time I had it done was $80 and 2-3 week turnaround. Might be more now but call him.
 
Oct 25, 2006
92
0
6
Central Oregon
#11
I've done both with good results. Now I am going to try X-Dies to cut down on trimming. Initially it looked pretty good. But a couple of moves and now the brass is all mixed up so I'll have to start all over again.
 
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