Skaerflint
The Skaerflint is the standard weapon of every military in the Known World, made by every city that has smiths. Nobody arms soldiers entirely from a foreign supplier and no one sane would. Forgegate's are better than most, and the difference is the lock: a mechanism that takes precision the other cities can match with effort but not at Forgegate's scale, so a great many Skaerflints in the world are locally made stocks and barrels built around a Forgegate-marked lock. Clearhold makes its own entirely and they are excellent. Stormharbor's are heavy, plain, and last for generations.
The one fact
It loads at the muzzle, and that single fact decides the shape of warfare in Teraell. A man reloading cannot do it lying flat. Every shot has an exposed moment attached to it and everyone on both sides knows when the moment is coming. This has produced an almost universal doctrine: fire by turns. One element shoots while another loads and watches. No unit moves without cover from another. A Haerman alone is a Haerman in danger, and being separated from your Roeta is the most dangerous thing that can happen to you short of being shot.
The shot
Powder fouls the barrel, and rifling would foul worse than a smoothbore if the ball needed something to grip. It does not. The Skaerflint fires a conical shot with a hollow base, cast slightly under the bore so it drops down a dirty barrel without forcing; on firing, the gas expands the base into the rifling. Loose going in, tight going out. That is what makes the weapon both accurate and quick, and why a barrel goes sixty or eighty rounds before it wants attention rather than twenty. What limits sustained fire is the powder and shot a man carries.
The lock
Clockwork lock mechanisms give more reliable ignition than any purely mechanical flintlock, a faster reset between shots, and less sensitivity to weather. The barrel provides the accuracy; the clockwork provides the reliability and rate.
Rain
Rain is the real constraint. A sprung pan cover, a projecting hood over the lock, and a tight cartridge carry a Skaerflint through drizzle and sea spray; none of it carries a man through an hour of steady rain. Eventually the water gets in — on his hands, on his Poeddra, into the powder long before it reaches the pan. An army caught in heavy rain is an army using blades.