I've shot lots of 10mm pistol bullets in my .40 sidelock from 140, 150, 160, 180, 200, 220gr cast pure lead. They are a great option, I shot plenty of jacketed 10mm's too, they just needed to be sized to .397 instead of the cast bullets at .40. I had a 1:37 twist, this next one will be 1:32 or...