I was doing some digging, regarding the Webley & Scott Mk II flare pistol, which DAM included with their Furiosa figure. That led to some images of the H&K P2A, which VTS has supplied with some of their Darkzone releases.
Runway SubCal offers adapter inserts, which allow the flare pistol to shoot .22 LR and .45 LC cartridges, and .410 shotshells. It would be pretty easy to make a 1:6 replica of the insert, to add to the kit.
While the old Long Colt is both traditional, and lethal, I think one might benefit from an adapter in 9mm, .357, and .44 Mag or .45 ACP.