I located something interesting in my Google search for something else ... Information on the .41 Short Rimfire Cartridge for use in Derringers:
According to Cartridges of the World, the .41 Rimfire consisted of a 130 grain (8.4 g) lead bullet propelled by 13 grains (0.8 g) of black powder in its original load. The round produced a muzzle velocity of 425 feet per second (130 m/s) and a muzzle energy of 52 foot-pounds force (71 J).
8 grams at 130 m/s (71 Joules) for a weapon designed to be compact, short range and low recoil seems like a TL 4 "kissing cousin" to the Traveller Snub Pistol. By TL 8, they had better PROJECTILES to shoot!