Bullet Sticking In End Of Fired Case ?

[jsthntn247]

I have a 7-08 with .010 neck clearance over loaded round diameter. After firing I deprime the brass with a Redding neck die with a bushing that sizes the neck down half of my final diameter. I then anneal, clean, then run through a fl die with bushing that sizes the rest of the way down. If I do it in one step I get the same thing your seeing.

 

[el matador]

I've seen this happen before and I don't believe it has anything to do with the length of your chamber. I also see the opposite thing happen after sizing with a bushing die - the neck is flared out at the mouth. I don't know the exact reason it happens but I would guess the brass is springing back more at the case mouth than in the rest of the neck. I've never seen any adverse effects from reloading such brass.

 

[Bullet bumper]

I have used all kinds of sizing dies, bushings , collets etc but never seen any flaring or closing of the case mouth like the OP experienced .
It's one of those things where you have to start eliminating suspects one by one until the culprit confesses .
Lack of a good chamfer would cause me some problems with bushings .

 

[Mikecr]

Correct me if I'm wrong here, but the case head goes against the bolt and when it is fired the case expands out to the sides and shoulder forward to meet the chamber, right ?

This could happen, maybe, maybe not.
With big headspace clearance primer strike/ignition drives the case forward until it is stopped from going further forward. The case then expands, thinnest open ended brass first(necks), then shoulder, then further down the case. This expansion goes into chamber walls, gripping them, and the brass would normally stretch back to the bolt face where it happens to be gripping least(near webs). You can't unstretch brass, so continuation of this leads to casehead separations.

But if that primer striking/ignition drove neck mouths into chamber end, then those mouths would expand way less than the rest of your neck area(especially with mind-boggling 8thou clearance).
The mouths could also be allowed so little clearance that springback after expansion still leaves them in interference fit for cal.
The only other thing that comes to mind is a tapered neck chamber that was horribly done.

I agree with Bullet bumper, that nothing in die sizing would lead to this.
It was chamber sizing/forming on firing to left them that way.
If I were you, I would stop firing anything in it, and have a gunsmith take some measurements.

 

[TwoMore]

were these light loads? i notice you said you cleaned the soot. just a stab but maybe with a lighter load somehow the case isnt sealing at the end or even expanding totally there
edit, did the soot make it to the shoulder

 

[TwoMore]

ok so this thread got me thinking , and I just so happen to be workin on a 7rum AI just for the 195 and i just fire formed 100 pieces of brass i used an old sendero barrel that i used the same reamer on for fire forming, my reamer is a .3164 neck and i turned my brass to .015 from necked down 300 rum rp brass when I measure my fire formed brass it is all .315 at the back of the neck till right at the end it is .314 all of this brass was shot about 10 grains shy of running loads

 

[Wedgy]

were these light loads? i notice you said you cleaned the soot. just a stab but maybe with a lighter load somehow the case isnt sealing at the end or even expanding totally there
edit, did the soot make it to the shoulder

No, this was a pressure test, carbon only on the necks, and certainly nothing under loaded.

 

[Deleted member 46119]

7mm RUM

.320" fired case OD
.313" loaded round
Fired case shoulder 2.460"
Necks turned to .014"
Length 2.846-2.848"

On 5 of the 14 fired cases a bullet won't go back into the fired case, it gets stuck on the case mouth, the rest of the neck has clearance. Doesn't matter about the length, some are the 2.846" and some are the longer ones. In order fired they are the 2nd, 4th, 10th, and 14th so it wasn't a progressive worsening. They aren't dented so I was thinking a carbon ring but borescope said no, a light cleaning with Eliminator was down to metal, so no ring. I ordered a Sinclair chamber length gage but I guess that's a matter of how much you turn your brass. In the photo(spun with steel wool to remove carbon) it looks like the case tapers a little at the end of the mouth but I couldn't measure it, wall thickness is the same.
Options are;
1) turn the necks down a little more; don't really want to as the rest of the neck has clearance.
2) trim the length down a little it's just a short chamber
3) Wait for the chamber length gage
4) I am totally missing something, worn reamer but why on some and not the others ?

SINCLAIR INTERNATIONAL Sinclair Chamber Length Gage | Sinclair Intl

I can't see where Wedgy has gone with this.

1) Anneal before sizing. The RUM design works the heck out of the neck and shoulder.
2) Measure your datum to shoulder for every case. No more than +-.001
3) Trim the length. 2.840 +-.001. Extra and variance of .006-.008 is IMO not good.
4) Chamfer and debur. Inside chamber is no more than %70 of neck thickness. Debur is debur, not chamfer.

Last is a long address of your neck wall thickness.

Most neck wall thickness on WSM, Nosler, RUM seems to come from the factory at .0165+-.001. You have not said what your neck wall thickness is so I calculated it at .0145. The specs I can find shows .0165 to .018. For hunting/tactical chambers I skim turn. Might even leave a little bit of unturned in spots.

Based on your fired brass your chamber has a .322 neck. .320 + .001 per side spring back. With a loaded round at .313 you have .0045 on each side for clearance of an unfired round. IMO too much, It does not take much to bring that number down. Instead of turning down to .0145 turn down to .0155.

Summary
Anneal
Trim to 2.840
Turn to .0155

The order you turn vs trim is also important.
1) anneal.
2) size with a bushing or expander ball .002 larger than "normal".
3) neck turn just nicking the shoulder neck junction.
4) neck size down to "normal"
5) trim
6) chamfer and debur
7) load

 

[Deleted member 46119]

This is not a case of my way or the highway this is just my opinion and procedures.