Your thoughts have some merit. I think a different bullet design would solve the problem.
That looks to be the lee designed for the 7.62x39?
I went and bought one of the 6 bangers a while back, folks said it would work in the K31's. Mine don't like it. BTW mine did shave when the would chamber.
Went back to the RCBS 165 sil bore rider. I waqs tempted to go the 6 banger route on that on too. Then decided quality was better than quantity.
I would sure like to have the same bullet that would drop at .310 and another at .313, with a proper sized nose for each.
This particular design has worked very well to excellent in evrything it will fir properly in.
jeff