I would go with the 44 mag barrel,and if you decided it was'nt enough,ream it to 445 supermag. I've got 1600 plus fps.with the 300 gr.Hornady with the 44 mag and 1975 fps. with the 445. The 445 shot 1 1/2" at 100 yds. with the old oversized barrel that I had,and was almost the equal of the 444 Marlin in performance. The 44 mag in a handgun may be a handfull for you if you're not used to it. Digger