Forster Micrometer Seating Die Issue

Nov 1, 2017
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5
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#1
So I have recently bought a forster coax press with forster FL Sizing die honed to give me .002 neck tension and a forster bench rest micrometer seating die. I am using Lapua brass, vargat powder, and hornady 140gr eld match. I have found my lands and know what my seating depth should be from the ogive measured with a Hornady Compator 5-26. I have noticed when seating my bullets 6 or 7 will come out perfect and then a few in will seating 5 or 6 thou deeper than the rest of them. I have measured my bullets and all seem very consistent my brass is all trimmed and set even and my powder load is not compressed and none of the primers are sticking out further.Does anyone have any idea what might be causing this ? Thanks!
 

mijp5

Gunny Sergeant
May 7, 2009
4,619
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#2
The only way to seat every bullet exactly the same is to seat a few thou short, measure, adjust the micrometer, seat again and measure. Even in the most consistent bullets, you will see some variance.
 
Nov 1, 2017
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#3
It just seems really strange that I can go several rounds and they all be identical then just one jumps a significant amount like that. And after measuring 20 of my elf match they were all within .0005 of each other from bullet base to ogive
 
Nov 1, 2017
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#5
Not that I can feel. I don't turn my necks but I do use the honed die which brings my outside case neck diameter to .2880 and loaded rounds measure .2890 every time I check one
 

mijp5

Gunny Sergeant
May 7, 2009
4,619
1,702
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#6
My Berger hybrids are usually within 3 thou of variance but I always do the procedure above to get the exact seating depth
 
Aug 7, 2014
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Gillette, WY
#8
Not that I can feel. I don't turn my necks but I do use the honed die which brings my outside case neck diameter to .2880 and loaded rounds measure .2890 every time I check one
Try a nice, slow, smooth seating process and check again. Your numbers don't seem quite right, that is 10 thou of tension.
 
Nov 1, 2017
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#9
My Berger hybrids are usually within 3 thou of variance but I always do the procedure above to get the exact seating depth
I will be using this method going forward. I was just worried I was doing something wrong that might be an easy fix. still doing load development but last load was 7.3 SD and 26 ES over 10 rounds so I'm closing in there at least
 

whatsupdoc

Duck season
Dec 12, 2017
306
160
43
Long Island NY
#11
Played this game before, tried different methods to improve seating consistency. I now clean the inside of the case necks with a bronze brush on slow speed on a drill. I typically get +or - .001 variance for about 95% of my seated bullets.

Forgot, I anneal every time and use a mandrel.
 

MTyotehunter

MTyotehunter
Apr 5, 2012
400
7
18
Montana
#13
I went away from micrometer dies and got more consistent seat depths. Forster standard “bench rest” or whatever they call the non micrometer die is a great die.
 
Likes: FishDr

mijp5

Gunny Sergeant
May 7, 2009
4,619
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#14
A seating die is not a set and forget tool. The seating stem sits on a part of the ogive smaller than the bore diameter, therefore there will be variance dependent on the bullets. A seating stem with a diameter of bore size would solve most of this, but nobody makes this. David tubb is the only one who made a seater with a bigger stem, but it is still not 100% perfect. For example, if you are seating 6.5 bullets, the stem would have an inside diameter of .256.
 
Nov 1, 2017
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#15
I think it has to be the pressure I am applying to the press because I went and tried 10 more just to be sure and went very slow and applied the same pressure on the ram and all but one bulelt came out to 2.285 base to ogive and the odd ball came out 2.2835 just a little bit shorter.
 
Nov 1, 2017
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5
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#16
Played this game before, tried different methods to improve seating consistency. I now clean the inside of the case necks with a bronze brush on slow speed on a drill. I typically get +or - .001 variance for about 95% of my seated bullets.

Forgot, I anneal every time and use a mandrel.
I dont anneal and I use a ball in my FL sizer die that may be my issue.
 

spife7980

Full Member
Feb 10, 2017
3,769
794
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TX
#17
How hard were you leaning on it to make the press flex 5 thou? I just take mine until it contacts the hard stop, I don’t flex on it after that fact
 

mijp5

Gunny Sergeant
May 7, 2009
4,619
1,702
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#18
How hard were you leaning on it to make the press flex 5 thou? I just take mine until it contacts the hard stop, I don’t flex on it after that fact
I don’t understand how pressure differences are inducing variance. I use a cam over and that’s about it. With my 6.5 loads, when seating, I can literally pull the handle down with a light touch of my pinky. I let the cam over take over after.
 

spife7980

Full Member
Feb 10, 2017
3,769
794
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#19
Yeah I know but that’s the variable he thinks was different. One would have to really lean on the press to get it to flex that much.
 
Jun 13, 2008
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#21
I don’t understand how pressure differences are inducing variance. I use a cam over and that’s about it. With my 6.5 loads, when seating, I can literally pull the handle down with a light touch of my pinky. I let the cam over take over after.
Try adjusting your seating die until the press does NOT "cam over".

Some would argue you shouldn't be doing that with sizing either, but you surely don't need to for simply seating bullets. Adjust it until the bullets are seated properly at the stop of the press.
 

mijp5

Gunny Sergeant
May 7, 2009
4,619
1,702
113
#22
Try adjusting your seating die until the press does NOT "cam over".

Some would argue you shouldn't be doing that with sizing either, but you surely don't need to for simply seating bullets. Adjust it until the bullets are seated properly at the stop of the press.
The cam over for seating is extremely gentle and serves for consistency. I’ve never been able to get consistent seating without the shell plate just touching the die.
 

ruebarb

Sergeant of the Hide
Feb 7, 2018
203
61
28
Littleton, MA
#23
Not that this helps your Issue, but with my Reading Mic Die and the VLD seating Stem, I get +/- 1 thousandth on my Rock Chucker for Hornady 140 ELD M, Lapua Brass. My brass prep isn't that great either with these results.
 
Aug 7, 2014
835
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Gillette, WY
#24
Take your 6.5 comparator and caliper and measure a few bullets, your variance may be in the bullets themselves.
I'm lost on the stoppage of a press, the stop is after a camover.
Also, if your rifle has over 400 rds down it, your seating depths become less critical, even on a new barrel, once your seat depth is found, going closer to the lands will affect the accuracy, seating a little deeper not so much. If you have to adjust your die for each bullet, I'd be looking elsewhere in your loading process to figure it out.
 

Strykervet

Resident Phoenix Eye and Dim Mak Instructor
Jun 5, 2011
2,673
837
113
42
Pierce County, WA
#25
Some new Lapua brass will have tighter necks, especially the .308 but also others. I use those dies and I had all sorts of problems seating until I got a sizing mandrel that opens it up, then it goes through the sizer (on the Dillon I can use the trimmer die to do this or just run it through the sizer again).
 
Nov 1, 2017
44
5
8
#26
Take your 6.5 comparator and caliper and measure a few bullets, your variance may be in the bullets themselves.
I'm lost on the stoppage of a press, the stop is after a camover.
Also, if your rifle has over 400 rds down it, your seating depths become less critical, even on a new barrel, once your seat depth is found, going closer to the lands will affect the accuracy, seating a little deeper not so much. If you have to adjust your die for each bullet, I'd be looking elsewhere in your loading process to figure it out.
The only reason I am being so OCD now is I am trying to figure out my best seating depth for my rifle I just started loading on my own and the other guy was using like .100 jump and I wasnt having any luck at all with that. I moved down to .020 jump and got about 3/4 inch 10 shot group at 100 yards with an SD of 7 and ES of 26. If you take the cold bore shot out I got SD of 5.3 and ES of 14. I think I am closing in on a solid load but I wanted to check seating depth as one last factor.
 

arm017

Sergeant
Jun 5, 2017
404
100
43
Texas
#27
Ah I've played this game. And I solved it by going to wilson hand dies. Those Forster micrometers have not been reliable for me or my team. Forster in general has seemed to take a step back in quality recently. Not sure what the case is whether it is with their springs or what? But I was running in to the same issues like you were saying, even accounting for neck tension (which I think is where you're real problem lies) - where I would go to seat and the first 10 rounds were on the money, but then it would sort of drift eventually leading to at least a 7 thou CBTO variation. I concluded it was the forster micrometer dies. I can't see your press or stroking method causing that variation? But this is all black magic anyways so who knows?

You can also try with less neck tension. Lapua brass seems to have quite a bit of spring back, and if you are shooting for the prescribed 2 thou neck tension, I was running into similar seating depth issues there as well. I have also seen people mix in brass with each other - where some has 2 x fires and another had 8 x firings that had been sized and thinned a bit in the case neck and mouth to account for difference. but once you've accounted for all the variables, the tooling would be the last thing swap out to see if that is the difference. And that is one that I would say might be worth it. seating depth does seem to matter in my experience.


Things that help consistency in neck tension in my experience =

keep the carbon on the case mouths (no SS tumbling)
lanonlin based spray lube to resize
Expander mandrel (maybe try with less neck tension)
annealing
Redding type s bushing dies or a honed forster FLS non bushing die.
 
Nov 1, 2017
44
5
8
#28
Some new Lapua brass will have tighter necks, especially the .308 but also others. I use those dies and I had all sorts of problems seating until I got a sizing mandrel that opens it up, then it goes through the sizer (on the Dillon I can use the trimmer die to do this or just run it through the sizer again).
Can you buy a mandel and put it into the FL sizer die or is it a whole other die? Thanks!
 
Aug 7, 2014
835
99
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Gillette, WY
#29
Can you buy a mandel and put it into the FL sizer die or is it a whole other die? Thanks!
It's a whole different setup, google expander dies, mandrels. If you go that route, you won't run your expander ball in your die, and unless you get some type of custom mandrels, you're into one size fits all again. Bushing dies are my answer. Just by what I read, I run a lot more neck tension than most to bring my loads in.
 
Last edited:

spife7980

Full Member
Feb 10, 2017
3,769
794
113
TX
#30
Whole separate die

This body

accepts these mandrels


which get pushed down inside the sized down case to open the neck up around it.
 
Likes: LG65CM
Nov 1, 2017
44
5
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#33
It's a whole different setup, google expander dies, mandrels. If you go that route, you won't run your expander ball in your die, and unless you get some type of custom mandrels, you're into one size fits all again. Bushing dies are my answer. Just by what I read, I run a lot more neck tension than most to bring my loads in.
Thats kinda what I was thinking it seems like to me they would kinda do the same thing with my die being honed, the next logical step to me is to turn my necks. Because up to now 100% of my resized cases the outside neck diameter come out to .2880 and leave me with .002 neck tension after I load.
 
Nov 1, 2017
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#34
If your die was honed for a certain dia, wouldn't running a case back through an expander ball negate what you set out to do?
Honestly thats a good point I kinda thought that the ball just pushed the neck out to the wall of the sizer die. I may try running the die without the ball and see if my neck changes?
 
Aug 7, 2014
835
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Gillette, WY
#35
Thats kinda what I was thinking it seems like to me they would kinda do the same thing with my die being honed, the next logical step to me is to turn my necks. Because up to now 100% of my resized cases the outside neck diameter come out to .2880 and leave me with .002 neck tension after I load.
OMG, ok, you turn your necks, you've just made your honed die obsolete. Let's concentrate on what you can control with what you have. Some of this shit is for advanced loading, turning isn't so much about neck tension as much as concentricity of a loaded rd.
 
Aug 7, 2014
835
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28
Gillette, WY
#36
Honestly thats a good point I kinda thought that the ball just pushed the neck out to the wall of the sizer die. I may try running the die without the ball and see if my neck changes?
There is no golden rule a measured .002" is some magic amount of neck tension, it's a guideline to work from.
 
Nov 1, 2017
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5
8
#37
OMG, ok, you turn your necks, you've just made your honed die obsolete. Let's concentrate on what you can control with what you have. Some of this shit is for advanced loading, turning isn't so much about neck tension as much as concentricity of a loaded rd.
Currently I dont turn my necks I was just thinking that would be the next step.
 

arm017

Sergeant
Jun 5, 2017
404
100
43
Texas
#38
Currently I dont turn my necks I was just thinking that would be the next step.

LOL We have all been through the house of milo. He makes you feel like a dumbass before he makes you a reloading god. But kind of makes you figure it out on your own- some real yoda shit.
 
Nov 1, 2017
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#39
LOL We have all been through the house of milo. He makes you feel like a dumbass before he makes you a reloading god. But kind of makes you figure it out on your own- some real yoda shit.
He has been really really helpful. It seems like I have every other step of my process down except this one which in my mind should be one of the easiest steps.
 
Aug 7, 2014
835
99
28
Gillette, WY
#41
LOL We have all been through the house of milo. He makes you feel like a dumbass before he makes you a reloading god. But kind of makes you figure it out on your own- some real yoda shit.
LMAO, I'm not good with detailed directions, a guy needs to walk into this before running.
 
Nov 1, 2017
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#42
I have a 21st century lathe setup, it collects dust and is neat to look at. There is a lot of options mentioned in this post to try before resorting to neck turning.
Ok if you were to start trying things what would be the top 3 and in what order would you try them? Thank you again for all the help
 
Aug 7, 2014
835
99
28
Gillette, WY
#43
He has been really really helpful. It seems like I have every other step of my process down except this one which in my mind should be one of the easiest steps.
It's your time, but IMO, you buy neck turning equipment for one gun that is not behaving, it is one expensive and time consuming journey, and I'm not sure the gains for a prs style rifle is worth it.
 
Nov 1, 2017
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#44
It's your time, but IMO, you buy neck turning equipment for one gun that is not behaving, it is one expensive and time consuming journey, and I'm not sure the gains for a prs style rifle is worth it.
I would much rather try the cheaper options first I don't think I am near good enough shooting to notice a difference in turned necks.
 
Likes: Milo 2.5
Aug 7, 2014
835
99
28
Gillette, WY
#46
Ok if you were to start trying things what would be the top 3 and in what order would you try them? Thank you again for all the help
1. Get the seat depth under control, by sorting bullets before seating, this will give you a baseline.
1a. Seat smooth with repeatable motions.
2.. Manipulate your neck tension, both ways.
3. Some do not agree with me on this, get the vld seat plug, or go to a caliber above die to seat the bullets, it will grab the bullet farther down the ogive and give more consistent seat depths, if you're doing load dev, cull the off ones and shoot the same depths, you can always waste culls at close ranges and never see a difference.
By the sounds of it, your powder charge seems good.
Try this for starters, turning for me would be a last resort.
Example: I shoot 2- 6XC's, Norma brass, softer than a big girls ass. Loaded rd measures .272" at neck, I run brass through a .267" bushing, and the one I partial neck size with a .266" bushing, just far enough down the neck where the boatail junction passes through, the rifle shot decent .267, a 266 partial size made it a shooter.
 
Jun 13, 2008
767
299
63
#47
I prefer to size without a ball, to SLIGHTLY (like...0.001" or less) smaller than intended, then turn around and run the casings over an expander mandrel to bring the ID to where I want it to be.

Alternatively, for casings that are not to be used in extreme precision, I just size them in the FL sizer WITHOUT the expander ball so I get 0.002-0.003" tension, and I roll on with no further action.

I've also used the expander balls (all floating carbide), and the ammo shot just fine.

That being said, everything in my press/dies that CAN float, DOES float. The expander ball, the expander assembly, any bushings, the die itself, the casing itself, the arbor IN the arbor die, the arbor die in it's ring, the arbor die in the press...

All of that is left intentionally loose, with the obvious exception of the locking ring on sizing dies and seating dies.

The result is that, unless I have some CHANGE, all my ammo is 0.004" or under TIR with anything like decent brass, and that is true regardless of whether I'm seating on my arbor press, or using conventional threaded dies.

-Nate
 

SL61

New Hide Member
May 5, 2018
4
0
1
#48
Ah I've played this game. And I solved it by going to wilson hand dies. Those Forster micrometers have not been reliable for me or my team. Forster in general has seemed to take a step back in quality recently. Not sure what the case is whether it is with their springs or what? But I was running in to the same issues like you were saying, even accounting for neck tension (which I think is where you're real problem lies) - where I would go to seat and the first 10 rounds were on the money, but then it would sort of drift eventually leading to at least a 7 thou CBTO variation. I concluded it was the forster micrometer dies. I can't see your press or stroking method causing that variation? But this is all black magic anyways so who knows?

You can also try with less neck tension. Lapua brass seems to have quite a bit of spring back, and if you are shooting for the prescribed 2 thou neck tension, I was running into similar seating depth issues there as well. I have also seen people mix in brass with each other - where some has 2 x fires and another had 8 x firings that had been sized and thinned a bit in the case neck and mouth to account for difference. but once you've accounted for all the variables, the tooling would be the last thing swap out to see if that is the difference. And that is one that I would say might be worth it. seating depth does seem to matter in my experience.


Things that help consistency in neck tension in my experience =

keep the carbon on the case mouths (no SS tumbling)
lanonlin based spray lube to resize
Expander mandrel (maybe try with less neck tension)
annealing
Redding type s bushing dies or a honed forster FLS non bushing die.
Why leave the carbon on the case mouths? And how do you account for the carbon when calculating neck tension?
TIA
 
Jun 13, 2008
767
299
63
#49
Why leave the carbon on the case mouths? And how do you account for the carbon when calculating neck tension?
TIA
1) Some feel that it helps to even out neck release force, and seating force, and that it may help prevent cold-welding of the bullets to the necks.

2) You don't. Your equipment is not anywhere NEARLY precise enough to see the difference...at least, not from the diametrical influence.

But it might be notable that Emil Praslick and the AMU are basically of the opinion that the ONLY verifiable and reproducible neck condition is CLEAN. "Clean" = nothing except metal.
 

SL61

New Hide Member
May 5, 2018
4
0
1
#50
Thank you for the information. Like most of the stuff it seems to me you just have try them and find what works best for you.

What about cleaning the neck then using a dry lube when seating the bullet?
 
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