this weapon would completely rule out most sniper rifles as it would have the same power and more due to it being a pistol.
We know Styg isn't really a
Gun Nut in real life, and firearms in UnderRail are really very much video game logic based. But, still, I wouldn't imagine that even Styg would do such a silly thing as leave damage numbers the same in different guns just because caliber or even cartridge are the same. Consider, for example, the 7.62x39 cartridge (AKA the 7.62 Soviet, or "The AK-47 round"), which I believe is generally what 7.62 UnderRail is supposed to be based off:
link to ar15comIt starts losing remarkable velocity (and thus power) after the barrel drops below 7", and even around 8" or so it's still much slower than rifle velocity, meaning it does a lot less damage and penetrates much less. And 7.62x39 is very much designed for short barrel use; if the idea was to base 7.62 UnderRail off 7.62x51 or x54R, then the power drop would be much greater because those are long-barrel cartridges (and the game damage and weights would make no sense at all, but again, video game logic). Plus, I don't know if you've ever shot high power, big bore revolvers, but it takes much longer to get lined up for a follow-on shot from a handgun than it does for a rifle firing the same cartridge. Also, handguns simply have less mechanical accuracy than rifles do, in addition to the human error which means nobody can shoot a handgun as well as they can shoot a rifle.
So, somewhat less power and effective range along with higher AP cost is the tradeoff for maybe not suffering move&shoot penalty. That sounds relatively reasonable.
That said, I've often wondered what the 12.7mm cartridge is supposed to be, in-game. If it's .50AE, OK, fine, that's what Desert Eagles shoot. But if it's supposed to be 12.7x99 (aka 50BMG), then trying to use that in a revolver would be hilarious. It would be like setting a grenade off in a mixing bowl and hoping all the shrapnel goes toward the bad guys.