Crono's right. They've been around for about a century or two.
The most common Connlaothi gun is a single-shot, flintlock musket. Rifling is about thirty to forty years old at this point, but it's a lot easier to find a musket with it than without it. Somewhere, there's an old sarge griping and ranting about new fangled guns that any little kid can pick up a shoot. A few armories in towns near the borders keep bigger arquebus type guns and train their troops in how to use them, just in case some hostile knight comes clanking down the mountain. Then there are the dragoon pistols given to the Dragoons.
I'll have to remember this, so it can be added to Connlaoth's info.