[Varyon]

If NMZ’s aren’t a significant issue, it might be possible to have magelocks that aren’t reliant on the wielder, via enchanted triggers (enchanting just the trigger lets you transfer to the newest model of rifle when needed). Ideally, an item with such a limited use would have low enough energy requirements for Quick and Dirty enchantment, keeping price low. If not, you could have single-use versions take the place of percussion caps. Without the need for exposed powder (the spell can create the spark in an enclosed environment), you could probably get away with making paper cartridges and loading those straight in, quickening reload time - although with muzzleloaders you’d still need to ram it home.

If NMZ’s are a significant issue, the above isn’t a great option, and you’d probably just have the same sorts of weapon as Earth at a comparable TL, albeit perhaps higher quality due to magical assistance during crafting.

For piercing-resistant foes, I kind of wonder how well a small arm equivalent of chainshot might work. Something akin to a shotgun firing (cutting) flechettes might also be useful. If all else fails, having rifles sturdy enough to be serviceable staves/clubs would be useful, as well as the previously suggested sword bayonet.