I can't speak to killing grizzlies or to the 329, but I have owned a 629 Mountain Gun for years and put a bunch of rounds through it.
With hot loads, it'll get your attention but it's not unmanageable by any stretch. The rubber grip does stress my skin in the web area of my thumb. It gets red and sore after a while.
With 44 SP loads, the gun is a pussycat to shoot.
You might PM BMT here on the 'fire. I've seen him work his 629 MG, and it's pretty amazing.
Neat pistols. How effective on grizzlies, I have no idea and hope to never find out! I bought mine as a camping pistol but the bears around here are a lot smaller than that.
-jeff
