Re: Can/ should i neck up 300Rum to 375Rum brass
It will wind up a bit shorter when you expand the neck that much. The necks will also be a good bit thinner. If you go that way, expand in steps and anneal along the way. Lube the inside of the neck well. If you anneal the necks first you may be able to fire form in one stage...using a trash bullet in .30 cal.with medium to full load of standard powder. Or the COW method of using a medium charge of pistol powder such as Unique and filling the case with Cream of Wheat. That way the neck has a chance of staying concentric with the body by being enclosed in the chamber. Anyway you try it may produce a bunch of split necks since that is quite a bit of expansion. JMHO
