4-5 months of muskets? Regular flintlock muskets? I don't ever make one, even though it's probably my first research topic for black powder bombs. It might be interesting to add an extra mechanic to the musket (I don't quite understand what you were suggesting, unfortunately, but going from power 29 to 30 seems like a cosmetic change? And the number of bullets is not the issue..)
What I would suggest is a "messy wound" mechanic, which means some weapons make more fatal wounds than others. Muskets, with their crude, squishy lead ammunition that distorts on impact, would be great candidates for that. It would add a damage over time component that might help it shine on harder targets. The same thing could be given to a few other weapons, the billhook comes to mind, even though in melee you mostly want to make sure your target is dead, otherwise you will be on their turn..