Really the only big limiter on fire-arms would realistically be the lack of industrialization making automatic fire-arms or even some semi-automatic weapons far more expensive to utilize than not. We're looking at a world now where any ammunition made would be hand-loaded on a bench and not flying through a conveyor built system that puts the primer in the casing and the bullet over the primer at a rate of a hundred a second. It'll be a world where bullets would be hand made at a rate of maybe a hundred every five-minutes. You could easily assemble a fully automatic weapon but using it would be a nightmare to the pocket book, you could use up a large part of your armies supply wagon firing a machine gun to kill five people.