Strange thing at the range today using IMR4064

[mugsie]

This morning I was shooting my usual load in my .308. 168g SMK, 46.8g IMR4064, .010 off the lands. I shot this many times before with no problems, using a variety of brass, mostly Rem or Lapua but also PPC and FC. This morning after two shots, I wasn't able to close the bolt and longer. Even without a shell in the chamber, the bolt wouldn't close.

After a suitable amount of cursing, I took the rig home and found the primer from the last cartridge in the bolt area. It looked pristine, no cratering, yet it came out. I noticed on the head of the brass a small mark of the ejector, but nothing out of the ordinary.

The temps this morning were in the low 20's, maybe 24 or 25 degrees. The primer blew out of a piece of FC brass. Has anyone noticed 4064 being temp sensitive? Certainly not with a lower temperature I would think. I'm thinking that maybe the brass was a little thicker, or maybe the primer was loose to begin with. Incidently, this was a Winchester Large Rifle primer. Usually I use CCI, but the hording taking place caused the shop to only have WLR's now, so I bought a brick.

Anyone have an ideas as to what could have caused this?

Thanks all....

 

[JeffinTX]

Re: Strange thing at the range today using IMR4064

FC 308 brass is notorious for being thicker/heavier, yet softer than any other brass around. The heavier brass will give a higher chamber pressure, along with the softer brass...you get the idea. Segregate the brass, at least the FC, as it will not hold up to "warmer" loads repeatedly.

 

[cooper_257]

Re: Strange thing at the range today using IMR4064

loose primer pocket from too many hot loads

 

[FLIGHT762]

Re: Strange thing at the range today using IMR4064

46.8 grains of IMR 4064 with a 168 OTM is a pretty stiff load for FC brass. Federal 308 brass is notorious for being a bit softer than other brass. I shoot a lot of Federal 308 brass and I wouldn't go past about 44.0 grains of IMR 4064.

 

[5R Milspec]

Re: Strange thing at the range today using IMR4064

my thoughts all so

your lucky the head didn't come off and leave the rest in the chamber.

 

[1SMALLJOHNSON]

Re: Strange thing at the range today using IMR4064

Hodgdon manual lists IMR 4064 with a 168 SMK @ 45.9 grains, 58.8 kpsi. And that's with probably a good 0.050" freebore too. You're running 0.010" jump, and almost another grain. You're warm, if not hot. Here's my advice:

If you're going to tickle the dragon's belly, best take AMPLE regard for safety. You dare change a primer or brass type, or shoot in different conditions, you'd better start the day by loading up a couple of "try" charges, at reduced load. Work up slowly. Remember: Your gun and your bullets and your brass and your primers and your powder...were all made by humans. Humans are flawed. You've got only one face. Try to keep it pretty.