I'm using imr 4064 in 308 mil brass. The powder is already compressing at 40.6 . I want to work up to 42.6. Is this going to be a problem compressing powder like this.
i have no idea. Needs testing.Shape and size have a profound effect on the burning rate and power generation of a powder
Military brass may have less case capacity?308 mil brass.
2.800 hornady match 178Need more info. What bullet? What seating OAL?
If you can't get 40.6 gr of IMR 4064 in a .308 case without compressing, something is seriously wrong. DON'T DO IT. Figure out what's wrong.
Jim
https://forum.snipershide.com/threads/7-62-vs-308-brass.6822996/7.62 mil brass does have less internal capacity due to the thicker case walls. The difference is not negligible, you do need to back down your loads a bit if you've worked up a load in typical 308 brass.D