This may be cheating, in the eyes of some, but I'd want a full-sized 1911A1, fitted with a .22 LR conversion kit, and a .460 Rowland conversion kit. For concealed carry purposes only, I'd prefer an alloy-framed commander-style .45, but I doubt that the lighter frame would last long if used with the Rowland conversion.
If limited to one weapon and no conversions, I'd want a 5" S&W revolver in .45 Colt, or a 5.5" Ruger Redhawk in .45 Colt. Both are capable (with judicious reloading), of launching a 225grain or heavier projectile at 1000 f/s or faster, which is adequate for large, but not the largest game. The Redhawk could be loaded considerably hotter, but the same loads in the S&W might bend it.
The same pistols could be down-loaded until their recoil is no more emphatic than a .22LR, while retaining much better game-getting potential from their heavier, broader projectiles. If allowed, I'd probably want the piece set up to fire .45 ACP from moon clips, also.