Thoughts on this please

[Philward]

In regards to the attached photos and the mask on the case. This is a once fired Peterson 7mmRM in a Browning x-bolt. It is not stretched to failure, at least I checked the inside for a groove using a paper clip and it's smooth all the way around. Rifle has had a case head separation and another that partially split, due too over sizing and loading too many times. That process had been remedied and the whole batch of cases are scrapped.

Question is has the chamber been damaged in that area, burned groove or carbon deposit possibly? Hunting rifle with not alot of shots going through it. How bad will this be for the cases if they are still used? The opposite side of case is clean and smooth.

 

[Philward]

Better photos, first ones looked clear on the phone but are pretty blurry.

Second picture is opposite side of the case, and they all show same thing.

 

[Veteran]

Nope, this is a common problem with belted magnum cases.
I had the same issues on my .300 WM.

Advice I got here was to bump the brass shoulder down .002 each time I reload them. What's happening is you are over compressing the whole case down onto that belt each time, and then when it is fired, it stretches it back out right at above the belt. It will metal fatique there in 3 firings or so, and you will have case head separation. Bump only the shoulder down and set the die not to press the whole case body down onto that belt.

You can also of course neck load your belted magnums, but many here and Eric Cortina believe that is not as accurate as full case resizing.

So, you do full case resizing but only to the extent, your shoulder bumps down .002 each re sizing.

 

[FEENIX]

Nope, this is a common problem with belted magnum cases.
I had the same issues on my .300 WM.

I haven't had that issue, belted or non-belted.

 

[Veteran]

I haven't had that issue, belted or non-belted.

It is a thing for sure. BELTED
cases mostly or more sensitive.

You just experiment with turns and settings on dies or with thickness of shell holder or both until you get shoulder bump only of .002 .

I had my dies turned down too much and was compressing the whole case body down onto the belt.

 

[FEENIX]

It is a thing for sure. BELTED
cases mostly or more sensitive.

You just experiment with turns and settings on dies or with thickness of shell holder or both until you get shoulder bump only of .002 .

I had my dies turned down too much and was compressing the whole case body down onto the belt.

As I said, I haven't had that issue, and I own a few belted cartridges and have been loading them for nearly 5 decades.

I even have one of Larry Willis' belted magnum collet resizing dies for those case bulging issues, but I have yet to use it.

 

[Veteran]

Here's a thread that I think has a lot of good advice.

Read through the whole thing.

Neck Sizing Vs. Full Length Sizing and Neck Tension

Ok, I don't want to start a food fight or anything, but I am curious what everyone on this forum has to say about this subject. I've seen the Erik Cortina video where he says neck sizing is just passe and so much old lore, and to just full length size for consistency. I've seen some other...

www.longrangehunting.com

 

[cdherman]

I think the concept of a .002 thou shoulder bump has been slower to reach the belted magnum crowd historically. I am betting Feenix was doing that for his belted mags all along. And has not had trouble. As also noted, the belt means the resizing die cannot resize as far down the case as it could with a non-belted case. Regardless if you doing a brutal max FL resize, or a shoulder bump. The die stops sizing higher due to the belt. If your belted magnum has pretty generous headspace, and if you adopt "shoulder bumping", you will likely eventually have some sticky cases. But you will not have case head separation.

I managed this with my cousin's 7 RM 40 years ago. Around 3-4 firing, resizing only to bump the shoulder back a couple thou (who really knows, I was using the "soot on the case" method at the time, lacking better tools), we got sticky cases.

Funny, at the time I threw out the cases that were sticky. In the meantime, I invested in Larry Willis collet reforming die, as did Feenix. And similarly, have not yet used it.

 

[FEENIX]

I think the concept of a .002 thou shoulder bump has been slower to reach the belted magnum crowd historically. I am betting Feenix was doing that for his belted mags all along. And has not had trouble. As also noted, the belt means the resizing die cannot resize as far down the case as it could with a non-belted case. Regardless if you doing a brutal max FL resize, or a shoulder bump. The die stops sizing higher due to the belt. If your belted magnum has pretty generous headspace, and if you adopt "shoulder bumping", you will likely eventually have some sticky cases. But you will not have case head separation.

I managed this with my cousin's 7 RM 40 years ago. Around 3-4 firing, resizing only to bump the shoulder back a couple thou (who really knows, I was using the "soot on the case" method at the time, lacking better tools), we got sticky cases.

Funny, at the time I threw out the cases that were sticky. In the meantime, I invested in Larry Willis collet reforming die, as did Feenix. And similarly, have not yet used it.

Yes, Sir, I am.

 

[Philward]

Nope, this is a common problem with belted magnum cases.
I had the same issues on my .300 WM.

Advice I got here was to bump the brass shoulder down .002 each time I reload them. What's happening is you are over compressing the whole case down onto that belt each time, and then when it is fired, it stretches it back out right at above the belt. It will metal fatique there in 3 firings or so, and you will have case head separation. Bump only the shoulder down and set the die not to press the whole case body down onto that belt.

You can also of course neck load your belted magnums, but many here and Eric Cortina believe that is not as accurate as full case resizing.

So, you do full case resizing but only to the extent, your shoulder bumps down .002 each re sizing.

These cases were new and this was the first firing so they have not been sized at all. The previous batch of cases this individual had been over sized/full length sized before I started doing a 2 thousandths shoulder bump, and annealing for that matter. Although being a new case the distance to the datum is 2.107 and after firing they measure 2.122. so a fair amount of stretch initially,

 

[2buffalo]

I have to use the collet die after 4-5 firings the 300 wm has hard bolt close. No idea what that mark is on your brass but I wouldn't be afraid to let her rip. Could be a mark in the chamber from your case head separation. I would pull the trigger if it were me. Just keep an eye on it.

 

[Veteran]

These cases were new and this was the first firing so they have not been sized at all. The previous batch of cases this individual had been over sized/full length sized before I started doing a 2 thousandths shoulder bump, and annealing for that matter. Although being a new case the distance to the datum is 2.107 and after firing they measure 2.122. so a fair amount of stretch initially,

Ok, I did not catch that the cases pictured had never been fired but this once and never resized and now they look like emminent case head seperation.

Only 2 things I can think of.

1) Your rifle has a headspacing issue and headspacing should be checked before anymore firing.

2) That brass if not purchased new, may have been fired before 2 or 3 times?? How sure are you the cases were brand new?

 

[cdherman]

I have to use the collet die after 4-5 firings the 300 wm has hard bolt close. No idea what that mark is on your brass but I wouldn't be afraid to let her rip. Could be a mark in the chamber from your case head separation. I would pull the trigger if it were me. Just keep an eye on it.

I like that thought. Some roughness where the prior case head separated and etched the chamber a little. That fact that the OP cannot detect a ring or groove makes case expansion a poor explanation for the outside appearance.

Ok, I did not catch that the cases pictured had never been fired but this once and never resized and now they look like emminent case head seperation.

Only 2 things I can think of.

1) Your rifle has a headspacing issue and headspacing should be checked before anymore firing.

2) That brass if not purchased new, may have been fired before 2 or 3 times?? How sure are you the cases were brand new?

Well, semantics here, but since a belted magnum headspaces off the belt, cannot really be a headspacing problem per se. But I get what you are saying. I just don't know how a reamer could cut a proper belt groove, but a grossly deep chamber. I myself used the term "headspace" earlier. I don't know that we have a proper vocabulary for "belted magnum with too long a chamber"......

Someone smarter than me -- teach me, does the reamer for a belted magnum cut the belt groove too? Or is it cut later.? I am no gunsmith, though I screw the occasional Savage together.....

 

[Veteran]

I like that thought. Some roughness where the prior case head separated and etched the chamber a little. That fact that the OP cannot detect a ring or groove makes case expansion a poor explanation for the outside appearance.

Well, semantics here, but since a belted magnum headspaces off the belt, cannot really be a headspacing problem per se. But I get what you are saying. I just don't know how a reamer could cut a proper belt groove, but a grossly deep chamber. I myself used the term "headspace" earlier. I don't know that we have a proper vocabulary for "belted magnum with too long a chamber"......

Someone smarter than me -- teach me, does the reamer for a belted magnum cut the belt groove too? Or is it cut later.? I am no gunsmith, though I screw the occasional Savage together.....

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Headspacing: Is GO gauge supposed to equate to never-fired brass?

I'm looking for the poor man's way to check for excessive headspace in a center-fire rifle. Obviously, the bolt should close without any resistance on brass that has never been fired. My question basically is: How thick of a shim can be placed between the bolt face and the fresh (I would try...

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