Short Chambered Barrel (308 Winchester)

Yes, it's not hard to bump up a bullet in an RCBS Rock Chucker press setup. I've heard that this press can generate ~60,000 psi. when it rolls over center at the top of the stroke. It takes very llittle effort to do it. When trying to bump up, I used to get stretching of the bump dies if they were made of 7/8” stock so, I took the bushing out of the top of the press and used stock that was much larger in diameter.  Even Drill Rod would stretch and that's pretty tough stuff. Having a thicker wall on the dies solved the stretching problem.

Bumping lead bullets  up is less desirable than sizing them down. It's better not to choose a throat that is over .309” and then everybody's 30 cal. bullets can be made to fit by sizing down. In bumping them up, die stretching and bump force make it very hard to maintain a consistent diameter unless you use a soft alloy and shoot them slow. My bump press design was made in such a way as to control where the taper started on the bullet as well as the bump force when the press rolled over center.

Yes, I used alloys of monotype and Foundry type to shoot in the 2500 to 2700 fps. range. This was to minimize wind drift. These alloys always cast very easily too which added to the consistency of the bullets. With properly sized bullets and my proprietary lube, leading was not existent.

I always figgered that using bumped bullets, match prepped Lapua brass in a 30 BR chamber and a match grade SS barrel, with a Stolle action, Jewel 2 oz. trigger, and a 36 power scope, the guns were capable of .3 MOA.  Now, shooting that well in the conditions was another story!!!

Tom