I think one missing point here is if the OP hand loads or not.
If he does not load his own then the 44 mag is the right caliber. There are some impressive 45 Colt rounds out there but I have never used them. 260 GR 1450 FPS and 1214 ft lbs.
"The difference between stupidity and genius is that genius has its limits" Albert Einstine
Did you hear about the latest study.....5 out of 6 liberals say that Russian Roulette is safe.