Calling all gunsmiths

[Joefrazell]

Hey everyone, I bought a bergera b14 Hunter in 30-06 for my wife about a year ago. Ive shot it a bit and just started reloading for it about 6 months ago. I started noticing some real strange cracks right where a typical case head separation happens. Its basically like a start to one. Now this is after only 1 reload on the brass. I've tried 3 different brass manufacturer's and all do the same. So I starting really looking at the factory brass that had only been fired with a factory load and noticed a very very faint cracking in the same area. It's very hard to see but it is there and appears to be a start of a separation. So I went ahead and have the rifle to my gunsmithing just to check the headspace real quick. It was right on the money. He said to send it in and see what they say. So I did. A month later I just got the rifle back with a clean bill of health and they said they cleaned and lubed it, shot it 3 times and everything is ok. So i just got back from shooting it and it's still doing the same thing. I also noticed that it's got a pretty noticable bulge right in that area towards the bottom of the case. ( Sorry not sure what that area is called). I measured it a s it's .006" of a bulge. My question is is this excessive and why I'm getting the issue? I'm going to call bergera tomorrow and see what they say but wanted to be informed by those who know more. Thank you

 

[Jud96]

Looks to me like the chamber is oversized and causing the case to over-expand, bulge, and crack. If you're seeing 0.006 of expansion compared to sized brass, that's huge and the problem is the chamber.

 

[Joefrazell]

Ok so when I resize a piece the largest portion of the bulge area only sized down .003" but still has a slight bulge to it. Not sure if this helps diagbose it. I guess if that area stretches .007 from the first firing and .003 Everytime after that it may cause the issue?

 

[Joefrazell]

I measured a factory non fired case from the same box of factory ammo and it's .007-.008 smaller then the fired and then once resized it's .003 smaller the fired case.

 

[Danny1788]

.007-.008" is way too much. Oversized chamber

 

[FURMAN]

If it is sizing .003 after firing then most likely it is NOT an oversized chamber. .003 sizing is typical. The growth from new brass to the fired brass of .007 is not uncommon with some brands of brass. If it were an oversized chamber you would most likely be sizing well over .003.

 

[FURMAN]

Do you have a better picture showing the "cracking"? That picture really shows nothing abnormal.

 

[Danny1788]

If it is sizing .003 after firing then most likely it is NOT an oversized chamber. .003 sizing is typical. The growth from new brass to the fired brass of .007 is not uncommon with some brands of brass. If it were an oversized chamber you would most likely be sizing well over .003.

Look at his picture .007" base expansion? Tells me over sized chamber. Not shoulder bump

 

[FURMAN]

.003" base expansion? Tells me over sized chamber. Not shoulder bump

I am completely aware of what shoulder bumping is. I actually just got off the phone with Hornady last week due to a PRC sizing issue. The tech told me they shoot for .003 sizing (not bumping). Case head expansion is expansion past the chamber reamer spec NOT an increase in firing based on new brass or sized brass. Op if you have better pics showing a real problem by all means post them but if you are not having extraction issues I see no problem with the brass in your pic.

 

[Danny1788]

I am completely aware of what shoulder bumping is. I actually just got off the phone with Hornady last week due to a PRC sizing issue. The tech told me they shoot for .003 sizing (not bumping). Case head expansion is expansion past the chamber reamer spec NOT an increase in firing based on new brass or sized brass. Op if you have better pics showing a real problem by all means post them but if you are not having extraction issues I see no problem with the brass in your pic.

I was thinking at the base due to his picture but it maybe just the pic

 

[FURMAN]

I am sure he is measuring at the shiny line ~.200 up from the case head in which case I stand by everything I have said. You really should not get any case head expansion. That typically happens at very high pressures and usually primer pockets are done by then.

 

[Danny1788]

To the Op it's a 30-06 right, what is the measurement at the base after firing? Not how much it grows. The actual measurement of the brass? If it's in spec it's just brass growth which is normal

 

[FURMAN]

To the Op it's a 30-06 right, what is the measurement at the base after firing? Not how much it grows. The actual measurement of the brass? If it's in spec it's just brass growth which is normal

This is the real question but if it were larger than spec he should be seeing difficult extraction. As far as actual case head you will need a mic not a cheap caliper.

 

[Joefrazell]

I will get some pics of the cracking. It's very very hard to see when not in person. Another thing is you can run your fingernail up the the case starting at the case head towards where the bulge area is and actually feel it but only in about 1/3 of the case head area. The other area is much smoother. My 300 win and my 6.5 I can't feel it at all. Case head is not expanding but slightly above which I understand is normal but it's not concentric, even expansion. I know there's a problem just trying to get an idea of what the problem is. I should be able to get more then 2 firings off a piece of 30-06 brass. I'll get a pic of the cracking in just a bit here