Pre-fit Barrel Headspace

Feb 10, 2017
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#1
Okay, so I'll be using a Savage style barrel on my build and am wondering how everyone sets the headspace. I want to just get go, no-go gauges and call it good, but I'll be in 6.5x47mm Lapua and I've been having trouble finding both a go and no-go gauge for that caliber. Can I do the same thing with a piece of brass? Is that safe to do?
 
May 12, 2006
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The Big Country
#2
It wouldn’t scare me to headspace off virgin Lapua Brass. Remove firing pin and ejector plunger first. Headspace to slight feel on bolt closing. Put a piece of scotch tape on back of brass and use it as a no-go gage.

John
 
Likes: MarkLeupold
Oct 31, 2017
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#3
Pull the barrel up hand tight with the guage in place. Remove the guage, and tighten with the wrench, recheck with guage. I don't want any force on any of my guages'. If you have never used one, the wrench will accept a 1/2" drive breaker bar, or torgue wrench. You will also want a very solid mount for the barrel vice.
 
May 12, 2006
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The Big Country
#4
Pull the barrel up hand tight with the guage in place. Remove the guage, and tighten with the wrench, recheck with guage. I don't want any force on any of my guages'. If you have never used one, the wrench will accept a 1/2" drive breaker bar, or torgue wrench. You will also want a very solid mount for the barrel vice.
He doesn’t have the gages.

John
 
Feb 10, 2017
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#5
He doesn’t have the gages.

John
Yes, I can get a No-Go pretty easily, but the Go is harder. Plus they seem really expensive for what they are. If I can do without, that'd just save me some cash. If anyone knows of a place to get 6.5x47mm gauges, I wouldn't be opposed to buying the pair for the right price.
 

MarinePMI

Battery Operated Grunt
Jun 3, 2010
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#8
Try calling northland shooter supply. He had gauges on hand for about any caliber I wanted to use for a prefit.

I only got a go gauge and used the tape method... but I d have to recommend getting both
And make sure both of them are from the same maker. Mixing gauges from different manufacturers is a bad idea...

Personally, a go-gauge is all I've ever used for pre-fits.
 

bohem

PVA's HMFIC
Jan 6, 2009
7,234
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www.patriotvalleyarms.com
#9
And make sure both of them are from the same maker. Mixing gauges from different manufacturers is a bad idea...

Personally, a go-gauge is all I've ever used for pre-fits.

What he said^^^

And dont bother pulling the ejector out, that is a waste of time and risk of losing little springloaded stuff.

The mechanical advantage of a 20tpi thread is so high that a trained hand can barely feel the engagement of the ejector anyway. Crank the barrel in til it stops hard on the GO and tighten the barrel nut. Pull the gage and go shoot.
 
Feb 10, 2017
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#11
What he said^^^

And dont bother pulling the ejector out, that is a waste of time and risk of losing little springloaded stuff.

The mechanical advantage of a 20tpi thread is so high that a trained hand can barely feel the engagement of the ejector anyway. Crank the barrel in til it stops hard on the GO and tighten the barrel nut. Pull the gage and go shoot.
It's going to be a Nucleus action anyway, so mechanical ejectors are nice, lol.

Thank you! That's what I need.
 
Feb 10, 2017
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#13
According to Pacific Tool and Gauge there is a 6 to 8 week lead time as the gauges are not stocked but made when ordered. They do seem to have the cheapest price I could find though. The other thing you could try is check for any of these since they are the same gauge: 6.5 x 47mm Lapua = 6 x 47 Lapua, 20 x 47 Lapua, 22 x 47 Lapua, 30 x 47 Lapua.
Yeah, I originally went to PT&G, but I've heard some really awful things about them and items they don't keep in stock, so I hesitate to order from them if it's not in stock.
 
Likes: MarinePMI

gpr

Private
Feb 21, 2017
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#16
Crank the barrel in til it stops hard on the GO and tighten the barrel nut. Pull the gage and go shoot.
Your suppose to have it tight on the GO gauge? I installed two barrels lately where I was tight on the go gauge. This made it so that some ammo was tight closing the bolt, even factory Hornady match ammo once in a while was hard to close the bolt.

I loosened the barrels and set them so that the bolt would barely not close on the no-go gauge (thus a little more head space) everything seems a lot better now. Am I installing these barrels wrong?
 

supercorndogs

Professor Dickweed
Feb 17, 2014
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#18
I use a piece of brass. I tighten it up against the brass, then back it off slightly. aiming for .001-.002 over the brass. Then i set my dies up accordingly.
 
Feb 19, 2017
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#19
You can just use the brass but should be a fire formed one from another gun I have seen Vergin brass lengthened in the shoulder area up to 15 thousands so a fire formed would work best and do it just like supercorndogs said good luck
 

MarinePMI

Battery Operated Grunt
Jun 3, 2010
2,486
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San Diego, Ca
#20
I think folks are missing how a barrel nut pre-fit barrel works.

When you screw the barrel on to the receiver and go-gauge until it stops, and then tighten the barrel nut, the tightening process pulls the barrel away from the receiver (thereby slightly increasing the headspace so it is just above minimum, in theory). The amount it is pulled away from the receiver is determined by the stacked tolerances of the barrel/receiver threads and the barrel/barrel nut threads.

I have had some barrels where the thread tolerances and chamber depth were close enough that it was causing problems chambering SAAMI spec ammo. In this case, a single layer of magic scotch tape (.0024" thick IIRC) on the back of the go-gauge will give you enough space to chamber any SAAMI spec ammo, without giving excessive headspace. Just remember to cut/trim the excess tape from around the go-gauge case head, so as not cause any wrinkles or folds that throw off the thickness...a sharp knife, run perpendicular to the tape will cut/rub through the tape so the excess falls away, leaving only a circle of tape on the gauge case head.

HTH...

BTW, a piece of brass if doable, but you need a new piece of brass every time you try to (lightly) seat the barrel. The barrel has enough mass when being threaded into the receiver to slightly crush the shoulder without you noticing. If you use the same piece of brass for several attempts, the brass will actually be shorter than you want it to be, from being crush ever so slightly each time the chamber butts up against the case shoulder.
 

bohem

PVA's HMFIC
Jan 6, 2009
7,234
646
113
Southeast, PA
www.patriotvalleyarms.com
#21
Your suppose to have it tight on the GO gauge? I installed two barrels lately where I was tight on the go gauge. This made it so that some ammo was tight closing the bolt, even factory Hornady match ammo once in a while was hard to close the bolt.

I loosened the barrels and set them so that the bolt would barely not close on the no-go gauge (thus a little more head space) everything seems a lot better now. Am I installing these barrels wrong?
Tighten it by hand til it stops on the GO.

The ammo issue you're commenting on could be a multitude of things including something that feels like a tight headspace but it's really the ammo being jammed into the lands.
 

Booche

New Hide Member
Feb 11, 2018
2
0
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South Carolina
#22
Tighten it by hand til it stops on the GO.

The ammo issue you're commenting on could be a multitude of things including something that feels like a tight headspace but it's really the ammo being jammed into the lands.
I have used the go gauge/ tape very successfully dozens of times. Had the issue of it closing tight a couple times. Tweak as necessary. Still make sure it does not close on go gauge with tape.
 
Nov 8, 2004
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#23
. . . When you screw the barrel on to the receiver and go-gauge until it stops, and then tighten the barrel nut, the tightening process pulls the barrel away from the receiver (thereby slightly increasing the headspace so it is just above minimum, in theory). The amount it is pulled away from the receiver is determined by the stacked tolerances of the barrel/receiver threads and the barrel/barrel nut threads. . . .
I agree with almost everything here, the exception is the last part of "the barrel/barrel nut threads." I don't believe that their fit has anything to do with the final headspace. It is as you said "the barrel/receiver threads." The nut simply pulls back on the barrel and the receiver and barrel thread contact will determine how far the nut can pull the barrel back.
 

MarinePMI

Battery Operated Grunt
Jun 3, 2010
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#24
Perhaps I wasn't clear, but I think we're saying the same thing. The barrel nut jambs against the front of the receiver, in doing so, any movement or shift that occurs, will be a result of the stacked tolerances of the threads between the nut and barrel, and the threads between the barrel and receiver. The closer the fit of these threads between the three parts, the less shift (headspace over that of the gauge) will occur.
 

Wannashootit

Gunny Sergeant
Sep 3, 2010
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www.biggorillagunworks.com
#25
^^
Which is why I always use an action wrench in addition to the barrel vise.
Many will just hold the barrel in the vise and tighten the nut- but the receiver will always rotate ever so slightly with the nut when it engages, increasing headspace.
Holding the action wrench while tightening the nut eliminates that movement
 
Likes: dannySH

dannySH

Sergeant of the Hide
Feb 13, 2017
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#26
^^
Which is why I always use an action wrench in addition to the barrel vise.
Many will just hold the barrel in the vise and tighten the nut- but the receiver will always rotate ever so slightly with the nut when it engages, increasing headspace.
Holding the action wrench while tightening the nut eliminates that movement
+1 here. After the new barrel is installed when tightening the nut in order to get a correct headspace what you have to have pressed is the action not the barrel. You can use an action wrench or a clamp vise holding the action.
 
Likes: padom
May 15, 2011
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#27
After you set the headspace using brass and .002in thick tape, remove the tape. Partially insert a new primer, bolt the brass to finish seating the primer. Measure this as your "zero headspace" dimension for future reference when setting your dies. And the difference between brass length with and without the seated primer is your headspace vs the .002 you tried to setup with the tape.
 
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