Are Fireweapons even viable?

So we started a new campaign and i decided to play as a Sniper (Rogue Archetype) in this campaign. My DM allowed me to combine it with the gunslinger a little bit, so that my sniper class extends to fireweapons aswell and I also get the gunsmith feat. aswell as a musket.

So... At first this was a bit of a style thing. Because this is a pirate campaign and Idk... I thought that would be suitable class for that setting. But the more I read about, the more weak it looks to me... I need around 11 GP per shot, a failure just damages my weapon, so I have to repair it regularly, I have to reload constantly for 1 full round (1 standart action with fast loading feat) and it does 1d10/x4 damage. Which sounds pretty high and atleast for low level it kinda is, but due to the definition of how fireweapons work, I don't get extra attacks in higher levels so even with level 20, I'm stuck with 1 shot per round.

Is it just me, or does that make that class very weak? and what to do, to make it a little bit more viable?

Use rapid reload feat + Cartridges, Alchemical to load a one handed firearm as a free action (as many shots as you want)
Use quickdraw to draw as many loaded firearms as you want (as many attacks as you want), but this is expensive and not that good. Use quickdraw and have a couple of firearms is nice to combine with rapid reload and alchemical cartridges.

There are ways to decrease the loading time another step so you can full attack with a two handed firearm, gunslinger has acccess to it, but I am not sure if other classes have.

Firearms, the big big advantage is: Early firearms resolve against touch AC within their first range increment. This means you will always hit with your shots, and you can even have deadly aim activated since firearms does not count as touch attacks for feats like deadly aim.