This video shows the main drawback behind why the rifle was barely used:
View: https://youtu.be/UhCx0b2ZC4Q
Logistics was the primary reason why this rifle just couldn't compete with regular gunpowder firearms, so yeah, whatever steam rifle we do make, unless Margret can find a way to make the gun and canister with fewer moving components & be overall less delicate, will most likely be relegated to a specialized weapon used for segies, outrides for sniping enemy leadership/monsters/arterially, or guerilla warfare.