You will probably be getting a lot of different opinions here. I will speak only from experience.
For revolvers, I killed a mature 6X6 bull with a FA .454 Casull, FA Factory 260 gr. JFP, wearing a Bausch & Lomb 2X6 scope, on 2 power as that is how I carry it. I also killed a 5X6 bull with an iron sighted FA, same caliber and load.
My third revolver bull was this year with a Custom .475 L, red dot sight, 400 gr. Hornady XTP. On none of these shots would I have preferred or even felt comfortable with a .44 magnum; I simply like the bigger calibers for the big bulls.
I am not saying the .44 magnum with the right bullets won't work; it certainly will, just giving my personal experiences and how I felt with each one.
As far as scopes go, I would go with your Leupold; 4 power is OK if you are used to it. I have killed several bulls with my .375 JDJ Contender wearing a 4X Leupy.
Gregg
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