Crazy never seen anything like this before

[williepete]

Well this is insane but here goes
History
223 lapua brass reloaded 14 times
annealed after every firing
forester f/l die with out expander ball
set neck tension with a Wilson expander mandrel
set shoulder bump 3k
1.4135
fired case 1.4165
Loaded 20 rounds to test
after sitting for a day went back to check everything and on 8 out of the 20 cases
shoulder bump changed from 1.4135 to 1.4185 WTF
pulled the bullets dumped the powder
and reloaded 8 different cases measured and they all were 1.4135 ok everything ok
24 hours later checked again and now 4 out of the 8 jumped back to 1.4185
strange thing is the cases can sit for weeks and no change in shoulder bump happens
it only changes when I load them up and seat the bullets what could be making the shoulder bump change
only after I load them up to shoot
this is the first time that I have seen such a thing
any feed back would be great

 

[cdgaydos]

Perhaps the bullet expanding the neck while seated transferred force to the shoulder… outward force on the diagonal shoulder translates to pushing the shoulder forward…

Do they chamber?

 

[SmokinJoe]

How are you measuring, what tool are you using? Parallel to what cdgaydos said, if you are using a stub gage seating the bullet could very well cause a change in your readings if there is any donut at all.

 

[williepete]

Perhaps the bullet expanding the neck while seated transferred force to the shoulder… outward force on the diagonal shoulder translates to pushing the shoulder forward…

Do they chamber?

No they wont chamber the no go gauge is 1.4180 the cases are 1.4185
this is a gas gun

 

[williepete]

How are you measuring, what tool are you using? Parallel to what cdgaydos said, if you are using a stub gage seating the bullet could very well cause a change in your readings if there is any donut at all.

I am measuring with a mitutoyo digital dial caliber with a short action custom comparator
seating the bullet with a forester mic seater
no donuts case necks turned inside and out neck tension checked with pin gauges neck tension set at 2k
use neo lube 2 inside the necks before seating, bullets go in smooth as butter.
got me stumped!

 

[6Creed73]

Doesn't make sense to me. If anything, the mandrel and bullet seating would push down on the shoulder, not pull it back out. I have seen what you are describing when using an expander ball though.

I'd recommend getting some neo lube #2 or graphite powder and coat the inside of the necks. I recommend that even if you weren't experiencing an issue...it just makes bullet seating more consistent in my experience.

*Edit...just saw you are already using Neo lube

 

[williepete]

Crazy thing is after loading everything up everything is ok shoulder bump at 1.4135 I also check seating depth with a comparator everything ok let sit overnight check again and jump goes back to 1.4185

 

[6Creed73]

Crazy thing is after loading everything up everything is ok shoulder bump at 1.4135 I also check seating depth with a comparator everything ok let sit overnight check again and jump goes back to 1.4185

Yeah, that's very odd. Brass does move, which is the reason I don't use the mandrel until I'm ready to seat bullets. I've noticed if I use the mandrel to set neck tension then let the brass sit for a few days, the necks sometimes change/spring back causing inconsistent seating.

But I've never heard of the shoulder moving, definitely not that much anyway.

 

[6Creed73]

If you are not shooting serious competition why worry about it. Shoot both conditions and see if there is a difference. You don't need to get OCD about something that doesn't matter. 223 gas gun doesn't ssound like a rifle intended to shoot small groups.

I think he's worried about it because it puts the case out of spec and won't chamber due to headspace being too long.

 

[dellet]

Is this a compressed load?

Might try a round with no powder to see if it solves the problem.

Then seating the bullet slower giving time for the air and powder to to adjust might help.

 

[fisherman987]

I would say your brass is too old after 14 firings and I would see if the same thing happens with fresh brass. I bet it won't. Something tells me that after so many firings, the neck and shoulder junction area has changed in some way that causes them to not hold their shape after a bullet is seated, especially since I'm pretty sure you are seating the bullet past the neck shoulder junction for magazine use. Try reloading exactly the same way with younger brass and tell us what happens.

 

[Walt Krafft]

After 14 reloads that brass owes you nothing. Pitch it in the recycle bucket and start with new brass.

 

[JMayo]

Imo make em so they fit without scrubbing but Not so much that they are rattling. Shoulder "exactness" isn't that important.
that small difference isn't over working , that is what sholder bump is all about.
Its not gonna effect accuracy in normal everyday shooting.

 

[williepete]

I think he's worried about it because it puts the case out of spec and won't chamber due to headspace being too long.

That's is what I worry about

 

[williepete]

Is this a compressed load?

Might try a round with no powder to see if it solves the problem.

Then seating the bullet slower giving time for the air and powder to to adjust might help.

not a compressed load but I like the Idea about seating with out powder and see what goes

 

[Rsadams]

After 14 reloads that brass owes you nothing. Pitch it in the recycle bucket and start with new brass.

My thoughts also...

 

[williepete]

My thoughts also...

I thought about that but no cracked necks and the primer pockets all pass inspection
I have a problem chucking 200 cases cause 12 are acting funny
I will see If I can get to the bottom of this
I am just glad that I always check my reloads the day I go to the range
on the wacked out cases the bolt might not have closed all the way and that can be a bad thing

 

[RegionRat]

Curious about your annealing method detail.

How do you anneal in terms of the neck-shoulder junction?
Could it be that the shoulder has become too hard and now responds differently to seating stress?

If you are destined to scrap these anyway... I would be curious to learn what happens if you flame anneal the case such that the neck-shoulder to shoulder zone is included in the heat zone, rather than just the neck?

 

[williepete]

Curious about your annealing method detail.

How do you anneal in terms of the neck-shoulder junction?
Could it be that the shoulder has become too hard and now responds differently to seating stress?

If you are destined to scrap these anyway... I would be curious to learn what happens if you flame anneal the case such that the neck-shoulder to shoulder zone is included in the heat zone, rather than just the neck?

I hear ya double R
A couple of years back I was getting inconstant shoulder bump
by just annealing the neck portion after that I started directing the flame at the shoulder and neck at the shoulder angle after that My shoulder bump became real consistent
I am not going to say perfect I am not trying to blow smoke up anyone's ass
but it will fall into 000.5 to 001.0 deviation I can live with that
I am going to skip the range today and fix the 4 rounds that went south and take a measurement tomorrow
And see If any thing changes If so I will trash the cases that made a change and go from there.

 

[williepete]

I would say your brass is too old after 14 firings and I would see if the same thing happens with fresh brass. I bet it won't. Something tells me that after so many firings, the neck and shoulder junction area has changed in some way that causes them to not hold their shape after a bullet is seated, especially since I'm pretty sure you are seating the bullet past the neck shoulder junction for magazine use. Try reloading exactly the same way with younger brass and tell us what happens.

I will keep you all in the loop