Fire forming problem

[superchip73]

Wow, its been a while since I have loaded any rounds. My son and I are working up some brass for his new Savage 6.5-284, we started fireforming some rounds @ 41gns. and one by one worked up to 46grns., thats when I noticed black powdery like stuff on the case, like powder blow by, so on further inspection I noticed that the case didn't form (blow out) out like the other cases, it even was lose in the neck die. Could it be the 20 deg. weather, the round in ?? was fired last and was out in the cold for a 1/2 hour. Thanks.

 

[nhkuehl]

Were you using a temperature sensitive powder? Was all the brass the same? Did you jam the bullet each time? I was bored one time (OK, lots of times) and I measured some loaded .223 rounds at room temperature and after leaving them in the freezer an hour and they had shrunk a couple of thousandths. - nhk

 

[JerrySharrett]

You are probably no where near the pressure required to fireform brass. For instance, I just ran a "forinstance" on QuickLOAD for your 6.5-284. If you had everything properly jammed against the bolt face either by jamming a bullet or jamming a false shoulder, etc., and you used a 100 grain bullet and 46 grains of 4831 powder you only generated about 24,000 pounds pressure. It takes in the neighborhood of 40,000 minimum to move cartridge brass. With that cartridge and bullet seating you have about 60+ grains case capacity. If you used 4831 (not the best choice though) at the 61 grain limit, you still only have about 55,000 pounds pressure.