Here's a pistol that is extinct and impractical by modern standards, but was the apex predator of its day. The Colt Dragoon was a historic firearm that was itself a shortened/lighter version of the Colt Walker. The Dragoon was intended to be used by mounted troops, hence the name. It weighed about 4 lbs/2 kgs, and was intended to be carried in a saddle holster (as opposed to a belt one). The weight, however, made it fairly accurate and handling recoil much easier. This Varangian Arms project is simply a Colt Dragoon with a few twists that revive the beast it once was, and make it something perfect for retro-future dinosaur hunting:
-A cartridge conversion cylinder (and perhaps ejector rod) able to handle .45 BPM (Black Powder Magnum).
-A somewhat lighter frame if possible (perhaps more akin to a Colt 1860 Army).
-Perhaps a shorter barrel (if used in a conventional holster), ranging from 14 cm/5.5 in to 20 cm/8 in.
-Optionally, hand grips with a Tyrannosaurus Rex on them could be attached to the grip.