Back to the 7.62x39, it has the same problem as many other chamberings, brass availability. The auto boys soak it up and there may be an availability problem. With the blackout you could cut, trim and reform 17 rem, 221,222,223, 357mag 360 DW. I had thought seriously about reaming a 357 out to Max, but looking at brass availability, why bother, I would rather go Herrett if I want to jack it up, as 30/30 brass is all over and cheap.