obligatory mention of the desert eagle as the standout example of a high-caliber handgun with a rotating bolt

as for the loading mechanism, the only modern analogue is the bond arms bullpup, formerly the boberg XR9

long-recoil operation is virtually absent in modern small arms, let alone in handgun form, but the technology is obviously available. the only examples i can think of (that are still in production) are the browning auto 5 and an AR10 alternative, the olympus arms vulcan

i guess what I'm saying is all the ingredients are there to be assembled into a new mars pistol, but what could be done to make it better than the old one, IE so niche nobody wants one?

well first is putting it in a caliber people can buy, probably 44 magnum or perhaps 44 AMP, if not just 50 AE. second is probably ergonomics. Just look at the thing: Would it even fit in one of those leather catchall holsters from the wild west? im not a bore axis snob, but it would certainly get roasted to a crisp by anyone who is. single action only and single stack magazines are fine for what would be a target shooting and maybe hunting pistol. in today's market, such a thing has to have optics compatibility, but given the lack of a traditional slide, I'm wondering if it might be better served by an AK-esque side mount on the frame. simple and strong for those who want it on, small and out-of-the-way for those who don't. finally, all reports indicate that recoil and muzzle blast were complaints from everyone who actually fired one. that calls for a compensator or more likely a brake. maybe you could offer threaded barrels for any madlads who think they can engineer a suppressor for a long-recoil magnum handgun.

the end result would still be very niche, but it would have few competitors, just the desert eagle and the automag really. the mars pistol is known well enough that it might see some sales as a made-to-order item because it isn't going to be cheap and it isn't going to be flying off the shelves.