Cause of split necks??

[Tommie]

A buddy purchased a Savage 12 BVSS in .243 for the prairie dog fields. The rifle performed fine on it's maiden voyage with all new brass. Now that the brass is once-fired, it's splitting the necks open 95% percent of the time. Houston, we have a problem.

My theory is that the factory chamber was cut with an overly large neck. New brass is soft enough to survive the ride but after being flame hardened and resized it splits at the second firing. I guess it's possible that he's run into the worst batch of brass ever seen on the planet, but I've never run into brass of any manufacture that was THIS bad. To determine whether or not the chamber is at fault, I'd assume the only way to know for sure would require chamber cast.

Are there any other possible causes for this problem?

Thanks for your help!

Tom

 

[rayjay]

Also measure a fired case to see how much the brass is expanding. There is some spring back so the chamber will be .002 or more bigger than the fired case.

I want to say that a saami chamber is .255 in the neck but I am going by memory [ which is to say I am guessing ].

 

[wnroscoe]

I had a 22-250 once that was doing the same thing. I was using new WW brass, it wasn't annealed properly from the factory and would split on the very first firing. I annealed the remainder of the brass, problem solved.

 

[Tommie]

Thanks for the responses guys! Please keep 'em coming!

The brass is Remington. I definitely inderstand that Remington brass is on the low end of the totem pole, but this is unusual.

I used a wrong term. "Flame hardened" is incorrect. I should have said "work hardened". Either way, I was referring to what happens to brass after it's been fired,and why we end up having to anneal it). My bad.

I just measured some once-fired cases and the necks measure .275" in diameter. The loaded rounds have a .272" neck. So much for my oversized neck theory.

Thanks again!

Tom

 

[wnroscoe]

anneal the remainder of the brass, problem solved.

 

[Tommie]

Ran a piece of brass through his RCBS FL sizer. Neck was sized to .265"

So the once-fired brass starts with a .275" neck, gets sized to .265" and then is expanded,by seating the bullet) to .272"

I've been using bushing dies for my rifles so long that I don't recall how much my standard dies crunched brass back in the day. Is .010",.005" per side) excessive for production dies?

Thanks again!

Tom

 

[Tommie]

Looks like the gun in question isn't the culprit after all. Apparently it's a case of poor quality brass combined with an overly-aggressive sizing die.

I passed along the good news to the owner of this .243 and he couldn't have been happier. Thank you everyone for the help!

Tom