Bullet Sticking In End Of Fired Case ?

[Wedgy]

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

 

[dok7mm]

The picture sure looks like the case O.D. is narrower at the mouth. My first guess is you're crowding the end of the chamber. The Sinclair chamber length gauge won't work in the tight necks, as you've found out.

I have also seen this happen to necks that have a heavy and deep chamfer, upon firing.

You should have a .312" loaded neck. What is your chamber neck ?
According to your fired neck OD you have .008" total clearance. Are you using bushings to reduce neck? How many and what size? Or a FL die?

 

[Mikecr]

I don't understand why you have so much neck clearance.

 

[TwoMore]

I don't understand why you have so much neck clearance.

i was thinkin the same thing, with a fired neck at .320 the chamber will be close to .321, maybe the end is springing back more.

 

[Wedgy]

The RP & Nosler brass I have are both .015" neck thickness which would give a .314" loaded round (.284 + .015 + .015 = .314"). Mine necks are cleaned up to .014"
The round I measured was one I did not fire in a ladder test, I pulled the bullet, then when I found this issue I simply tapped another bullet in with a hammer to get an idea of the size. Normally I would resize the neck then seat with a die, so that may account for the .013 instead of .012".
This is RP brass FL bumped to 2.458" neck bushing .310"

I don't know the chamber dimensions(hence the issues), I got it with 60 rounds fired.

Again, only 5 of the 14 fired cases had this issue and it is just at the very end of the case mouth and not dependent on length. I can get a bullet to go in a fired case with the VLD style chamfer tool but it is what I would consider excessive, chamferring to the outside neck and deep to where I'm actually shortening the brass.

The new Nosler brass I have is 2.840" unsized and untrimmed and may solve the problem altogether but I have ~100@ of this used brass I would like to keep firing but this lip issue.

Thanks for the input

 

[dok7mm]

Wedgy, this may not be causing your problem, but you shouldn't be using just one bushing to reduce your neck that much. I'd bet your resized necks are varying a great deal from case to case. I would use a .281" or .282" mandrel to open all necks to .002-.003 interference fit, prior to seating bullets. It should solve your problem.

 

[Dosh]

W, have you annealed any of that brass? I've read where some reloaders anneal most brass brands prior to ever reloading. Annealing has standardized neck tension for my brass. Good luck

 

[Wedgy]

Yes, it was annealed prior to this firing. I spun it with steel wool to clean off the carbon for the picture so it doesn't look like it has been annealed.

 

[Mikecr]

Is this only happening with new cases first fired?
Would you happen to know what shoulders measure (headspace-wise) on new cases?
Something has closed the mouths with firing. If not carbon, then maybe chamber end.

 

[MallardAddict]

Factory barrel/ chamber of custom? It almost sounds like the chamber is tight necked and not letting the necks expand enough while firing so after springing back neck diameter is too small.

Either that or neck thickness is all over the place in the virgins. Are you turning necks both inside and outside? On all virgin brass I inside neck turn each piece to make sure they are consistent then size and outside neck turn if needed.

 

[Wedgy]

A virgin RP case is 2.462"
My previously fired in another gun then resized case(the 14 cases I shot in this gun) is 2.460"
A fired in this gun case is 2.462"

I am thinking this is a short chamber. Still confused why only some of the shells are pinched at the mouth because it is not dependent on length of the brass.

Edit; the last question just popped up; this is a Krieger Sendero contour, not sure who did the chamber. It is only the very end of the case mouth that pinches the bullet, and only on 5 of 14 rounds(see post #1 for details)

 

[Bullet bumper]

You are turning too much off the necks . You don't need to clean up the neck 100% just do a skim neck turn about 75% clean up . Seat a bullet and see how much clearance you have . A few thou across the diameter would be ok.
You need to measure how long the necks are from shoulder junction to case mouth.
The OAL does not give any idea of any neck length variations . Necks could vary in length .
Another thing is make sure you are not crimping slightly on some cases in the bullet seating die .
Also the chamber internal neck length could be short or it could be malformed at the end of it . Reamer could have been a bad shape at the case mouth end.

 

[dok7mm]

You are turning too much off the necks . You don't need to clean up the neck 100% just do a skim neck turn about 75% clean up . Seat a bullet and see how much clearance you have . A few thou across the diameter would be ok.
You need to measure how long the necks are from shoulder junction to case mouth.
The OAL does not give any idea of any neck length variations . Necks could vary in length .
Another thing is make sure you are not crimping slightly on some cases in the bullet seating die .
Also the chamber internal neck length could be short or it could be malformed at the end of it . Reamer could have been a bad shape at the case mouth end.

Wedgy, If those 14 pieces of brass (once fired in another chamber, if I understand you) had different headspace and chamber length than your Krueger chamber, then you could be too long. Try some virgin brass, trimmed to spec and fire a few rounds and measure head to datum length. You can compare it to head to datum length of the old brass fired in other rifle, if you still have any that has not been sized. As a last resort, you could do a chamber cast, with Cerrosafe, as you don't have a reamer print. Good luck to you.

 

[Wedgy]

BBumper, these are RP cases I already had from another gun and have had RP anywhere from .016" to .0135" from the factory, quality is not #1 for them. I prefer .002-.005", chamber clearance, .008" is a bit much but I have this brass already and am hoping to use it. I don't think that contributes to this issue. ??
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 ?
If the length from the bolt/case head to the tip of the mouth is 2.846" (one of the short ones) and has an ejector mark so I know it was against the bolt, then it couldn't reach further in the chamber than one of the longer ones and get its neck pinched.
I slid a bushing over the case neck that fits fairly tight to the shoulder/neck junction and the fired cases are .002" longer than the unfired cases.
The seater is not crimping them, it turns freely when I release pressure.
I'm thinking like you say the reamer was getting worn at the end, maybe past its prime.