If I were choosing between 45 and 50 I would go with the 50. I say this even though as my name implies, I shoot a 45cal Hawken. There are just so many more bullet choices with the 50. If you ever want to go elk hunting, many states have a 50cal minimum for elk. The big push for the 45s was the increased velocity. In reality this was done by using 165-180gr bullets. You can get 180gr .451 bullets and achieve the same results with the 50. By the way, I have 50 and 54cal in the cabinet also. It's just the old Hawken is a special rifle to me.