Go with the .50 cal and if the recoil is the thing you are concerned about try using some Black Mag'3 powder or one of the other ascorbic acid based powders like Goex Pinnacle or American Pioneer. These powders in the three F version deliver high velocity with very little perceived recoil compared with Triple Seven which has a sharp and uncomfortable (in my opinion) recoil. You should also consider installing a limbsaver recoil pad which I did as I don't like recoil either. With the limbsaver and Black Mag'3 I think anyone that can lift my rifle can shoot the 300gr. bullet with 90gr. of BM3 which killed my cow elk this last year. Personally I would not consider a .45 for any reason as you can shoot the same bullets in a .50 with the right sabot selection if you want to shoot light bullets fast and then you can shoot the heavier ones for elk.