Crazy never seen anything like this before

[williepete]

Perhaps you have formed a donut in some of the cases, and when you seat a bullet past the donut, it expands out the neck enough, but only at the very bottom, that your measurement tool catches on the slightly expanded neck-shoulder junction? And the measurement is funky because it's such a small amount of brass sticking out?

the cases have no donuts

 

[williepete]

You still have a reality that shoulders alone cannot spring back that much.

I suspect that your FL die is over sizing, lengthening cases, and then reforming them back down.
That it's adding energy to a significant length of the case body in this process, and this length is whats equalizing overnight (not the shoulders).
Just a theory,, not trying to jinx your plan.

good theory
being that this is the first time it has happened over thousands of resizing i don't know
I am still leaning towards the annealing those 8 cases were from the last batch of 20
that i annealed
and i am thinking that i bumped the annealear it is the most lease expensive annealear you can buy
the gas bottle is not supporter so it is real easy to move the torch ang get off target
I like the annealer a lot for what I do small batches compact does not take up much space but you have to keep an eye on ot when it is work and have to reload it after every 10 rounds.

 

[williepete]

What length have you trimmed your cases to?

1.750

 

[williepete]

cdgaydos said: 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…

The shoulder is not moving. What is happening is the resized case is so close to the chamber size that the bullet seating is causing the necks to enlarge(normal) but the enlargement right where the neck meets the shoulder causes the shoulder to now be larger right at the junction; imitating a longer shoulder measurement, preventing the case from chambering. Adjust for an extra thou of shoulder setback and it fill probably take care of the problem.

How are you testing the "won't chamber" ? Most AR's will resize/move a shoulder a thou or more when the bolt slams shut, or seat a bullet deeper if it hits the lands.

Frank

I resized those 8 cases with out annealing could not because the primers are still in the cases I am loading them up now and will shoot them today.

 

[williepete]

A puzzle & learning opportunity.
That the issue occurs with time (overnight), and on it's own, tells me it's brass spring back. The brass going to the lowest energy level it can, over time. Here also, the shoulder is seemingly going beyond where it ever was.

It's like there is energy added that initially springs back to provide desired HS, but spring back continues overnight -to a place it must have been before. After all, why would it go to 1.4185 if it hasn't been there, or even further out to ~1.419 at some point? Shoulders in themselves do not spring back so much, and no brass goes to where it hasn't been by itself.
It's even longer than fire formed by 2thou, so your chamber (your best die) is never putting the shoulders there. So it must be your FL sizing doing it.

For HS offending cases, what is the case OAL doing?

oal has not changed

 

[williepete]

if your running a crimp die it could be slightly crimping and shoving the shoulder down just a tiny bit, if not running a crimp die I have no clue

I have solved the puzzle with everyone's help would never of thought of this
I went back and read all the replies and this one has always stuck in my mind I leave no stones un turned.
Well I took the 8 cases in question and resized them to 1.4135, then put the powder in them
then seated the bullets in them,
this time I measured the bump after seating the bullets and everything good to go 1.4135 so I thought i am on track, the last step in my process is to crimp, Redding taper crimp die here we go,
this time I measured the bump after the crimp, I never measure the bump after a crimp what fore it's a crimp
what could go wrong I mean we are rounding third and waiving at the crowd loading up the truck and headed to the range well f**k me running the shoulder bump jumped from 1.4135 to 1.4180 after the crimp on the down stroke of the ram it is crimping on the up stroke of the ram it is pulling away from the neck and in my case pulling the shoulder out of wack this happened on the first two cases out of the eight
swapped out the Redding with a lee factory crimp die and no more shoulder bump puzzle
nothing wrong with the Redding the problem was in different neck thickness in the cases the ones with thicker necks would grab harder in the die making it pull.
To the man with the big green tractor thank you for throwing your post out their with out your thoughts I would still be in the weeds
Cheers to all now it's off to the range to meet my shooting buddies before the rain hits
thanks to everyone.

 

[Webster]

I have solved the puzzle with everyone's help would never of thought of this
I went back and read all the replies and this one has always stuck in my mind I leave no stones un turned.
Well I took the 8 cases in question and resized them to 1.4135, then put the powder in them
then seated the bullets in them,
this time I measured the bump after seating the bullets and everything good to go 1.4135 so I thought i am on track, the last step in my process is to crimp, Redding taper crimp die here we go,
this time I measured the bump after the crimp, I never measure the bump after a crimp what fore it's a crimp
what could go wrong I mean we are rounding third and waiving at the crowd loading up the truck and headed to the range well f**k me running the shoulder bump jumped from 1.4135 to 1.4180 after the crimp on the down stroke of the ram it is crimping on the up stroke of the ram it is pulling away from the neck and in my case pulling the shoulder out of wack this happened on the first two cases out of the eight
swapped out the Redding with a lee factory crimp die and no more shoulder bump puzzle
nothing wrong with the Redding the problem was in different neck thickness in the cases the ones with thicker necks would grab harder in the die making it pull.
To the man with the big green tractor thank you for throwing your post out their with out your thoughts I would still be in the weeds
Cheers to all now it's off to the range to meet my shooting buddies before the rain hits
thanks to everyone

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

.I don't think you mentioned what bullets your using. Do they have a crimping grove. I never crimped. Can anyone comment on, should you only crimp bullets with a crimping grove? I get the impression guys are crimping bullets without a crimping grove. Wouldn't this distort the bullet shape. If you need a crimping grove you cannot try different seating depths. Is neck tension meaningless if you crimp?

 

[williepete]

.I don't think you mentioned what bullets your using. Do they have a crimping grove. I never crimped. Can anyone comment on, should you only crimp bullets with a crimping grove? I get the impression guys are crimping bullets without a crimping grove. Wouldn't this distort the bullet shape. If you need a crimping grove you cannot try different seating depths. Is neck tension meaningless if you crimp?

I use smk 69 gn.
If I don't crimp when the bolt slams home the seating depth changes
Just got back from the range everything back on track.

 

[6Creed73]

I have solved the puzzle with everyone's help would never of thought of this
I went back and read all the replies and this one has always stuck in my mind I leave no stones un turned.
Well I took the 8 cases in question and resized them to 1.4135, then put the powder in them
then seated the bullets in them,
this time I measured the bump after seating the bullets and everything good to go 1.4135 so I thought i am on track, the last step in my process is to crimp, Redding taper crimp die here we go,
this time I measured the bump after the crimp, I never measure the bump after a crimp what fore it's a crimp
what could go wrong I mean we are rounding third and waiving at the crowd loading up the truck and headed to the range well f**k me running the shoulder bump jumped from 1.4135 to 1.4180 after the crimp on the down stroke of the ram it is crimping on the up stroke of the ram it is pulling away from the neck and in my case pulling the shoulder out of wack this happened on the first two cases out of the eight
swapped out the Redding with a lee factory crimp die and no more shoulder bump puzzle
nothing wrong with the Redding the problem was in different neck thickness in the cases the ones with thicker necks would grab harder in the die making it pull.
To the man with the big green tractor thank you for throwing your post out their with out your thoughts I would still be in the weeds
Cheers to all now it's off to the range to meet my shooting buddies before the rain hits
thanks to everyone.

An expander ball will do the same thing. The only good expander ball is the one in the trash. Glad you got it sorted out!

 

[JB10]

I use many different bullets in several AR's. I never crimp. Never havd had a need too. Yes i have seen where seating depth has changed when i havd had to unload one in the chamber. But never have seen a difference in group size on paper.

 

[6MMsteve]

I was shoving shoulders down and couldn't figure it out, but it wasn't happening every time so I thought I had the crimp away on the 223 die but I didn't, I also just figured this out 2wks ago from 3yrs ago, thought I would pass it on glad it helped, 223 I just throw together but I learned they all have to be looked at carefully...low brain function on my part

 

[searcher]

I thought about that but I use tempilaq to check temp
and it is on the money
The most baffling thing to me is
a firer formed case is 1.4165
after it is resized it is 1.4135 after it is loaded and sits overnight
it grows to 1.4185 that is longer than the firer formed brass
how doe that happen.

It is normal for brass to spring back a bit after time. The more of needing annealing - the more it will spring back. When not using the expander ball, as you say, If it is springing back BEFORE you seat your bullets, it is a matter of not enough annealing on the shoulder. As there were no other influences, mechanically applied or not, at that point - that is almost certainly the problem. If it is only occurring AFTER you seat your bullets - and the load is definitely NOT compressed, it might have something to do with having way too much neck tension and when the bullet is seating, it expands the point on the shoulder just a tad which affects your reading - but to expand that much to prevent bolt from closing - it would have to be pretty extreme tension attainable with bushing dies. Sometimes these things work together to foul things up. My bet is the annealing process. I'd just check to see that you have a good inside neck chamfer and I'd hesitate using any kind of neck lube for use in a gas gun if your rounds are not crimped. I do use moly on my .308 M1A, but took some trial and error to get the tension just right where there was adequate tension without the bullet moving during the loading process. If you try to use bushings to give you the "death grip" on the bullet, that will cause problems with concentricity and bump measurement, if nothing else. If your brass has tight pockets, no signs of case separation looming, I'd just step up that annealing. My last thought is it might be worth looking inside your seating die to see if there is any foreign substance that might be messing you up. Not likely - but worth look just to rule it out, given this issue arises when seating. Good luck on that!