I'm just going to add in my two bits, though I rarely ever talk on the forums:

A couple years ago, I made an aborted effort at writing up some historically reasonable firearms rules for D&D. (It wasn't pretty, as it kinda used mixed rules from 2nd and 3rd Ed.)

I saw someone add that a skilled ACW Musketman could put off 10 rounds in a minute. A round every six seconds, I'm presuming they're referring to a muzzle loaded Springfield 1861/63 or 1853 Enfield, as those were the most commonly used firearms. The reality is, plainly, no. 3 rounds a minute is what was expected, and it's going to foul up on you bloody quick.

Lastly, on Mount and Musket: I'm not really impressed by it, but... since Battle Grounds 2 isn't really played anymore, I guess people have to get their musket fix in somehow.

going to toss in my two cents here.

On adding guns to D&D, don't. It destroys the flavor of the game.

While this is just my opinion, I like to stick with it.

On the historical note. I saw a video about an indian and a musket shooter, aimed at killing the myth that rifles fired faster. The musket shooter took his time loading the gun, the indian got off three arrows and moved in the same time period. Add that to the fact that beyond 50 foot the musket was terribly inaccurate, I do not see the value of the original guns being added to any game.