The fishing guide that killed the bear with his 3953 was using Buffalo Bore ammo. 7 shots with one round travelling across the chest cavity from side to side. I tried a 1013 conversion a few years ago and was never able to get 100 percent reliability from it using Double Tap 220 grain hardcast. I am shooting a 200 gr hardcast at 1140 ish fps from my glock 23 with no issues and am hoping for the same or better from the 4043. Karl Sokol currently has the barrel for a recrown and some chamber work to be able to chamber the big nosed bullet.