Tinkering today...

That old obsolete M1910 Winchester in .401 WSL. I can cut cases to make ammo but I always search for something a little more efficient. The 7.62x39 case straightened out has some merit. So it will be a 10x39mm if you will. the bullets are .41 Mag. 210 gr. and it is basically a .414 SuperMag rimless. Just wait till someone discovers it will drop right in a AR platform with a barrel, 7.62x39 bolt, and .350 Legend magazine. I can just see it now, the new 10mm Magnum AR15!

Anyway I digress... The wildly tapered 7.62 needs to be expanded out, then brought back in. After tinkering expanding to .35, .375, and .400 would be about ideal with elliptical expander balls. I only used .375 and .416 (too big). The .416 threw up a bulge that got ironed out FL sizing in a .41 Carbide die. That's the mid point bright spot. The rough expanding got the case mouth out of square just a bit so I cleaned that up.

The finished product looks like it should work. I changed the charge from H110 to 4227 and used Wolf LR primers this time. I think it is much better for the blow back action. You cannot hot rod it like others. Keeping the chamber closed while pressures peak, the recoil impulse, she's a different animal. Honestly the strong AR platform would do some neat things, getting pretty close to the .444 Marlin, or .429 GNR with 200-250 gr. class bullets.