Guns are radically effective against armor. Except... breastplates and full plate will stop them, so they shouldn't get a bonus against that type of armor. So, what we need is a special chart that compares weapon type to armor worn...
Actually... they aren't much good at ignoring armor. Modern weapons are, but the guns of the 15th - early 19th centuries were not much like modern guns at all, in that regard. Heck, a 18th C. Australian outlaw managed pretty well with a suit of homemade plate, for a time. (Ned Kelly.)
In fact smoothbore guns are worse against armor than a crossbow. A crossbow pretty much ignores everything except plate - and with a square or triangular headed bolt will ignore that pretty well too, though makes a smaller wound. The problem is that heavy crossbows are ssslllooowww, much slower than even a muzzle loading gun.
One of my hobbies is firing blackpowder weapons - and there are things that are seldom addressed by games. Smoke is very thick, and on a foggy day hangs around for a long time, and gives you a wicked cough. The stuff smells like rotten eggs. (I typically call it 'The Devil's Own Flatulence.')
From experience:
A bullet would do a better job of blowing through a 1 inch thick board than a crossbow, but a crossbow bolt would go through a quarter inch of steel that would bounce the bullet right off.
You can fire a wax candle through a 1 inch board using a smoothbore, and the candle wil remain largely intact, and can still be lit. I kind of expected it to go 'splut'.
I knew someone who was present when someone ended up with a freakin
hot dog through his arm, the idiot firing it expecting it to go 'splut'.
The lesson here? Things fired from a gun don't go 'splut'!
I have had almost no experience with either match or wheellock, mostly I have used the much, much more reliable flintlock. (Flintlocks were cheaper, faster, and more reliable than wheellocks - there's a reason that they spread so fast.)
My favorite gun is the Land Pattern Musket, or Brown Bess. Under field conditions the Bess would fail one out of sixteen shots, but since I have always had time to properly clean between each shot, I have never had a shot fail. (Or, to put it another way, I have never fired the gun under real field conditions - where you just don't have time to clean your gun properly.) A friend of mine has a Bess that saw over a century of service - what you might call a reliable weapon, if you were given to understatement.
The balls are big, and slow, and soft by modern standards - not much good for popping armor, but what it could do to bone was not pretty. Bones would not just be broken, but pulverized. (This got worse, right up into the ACW - in the ACW sometimes the bone was so damaged that amputation was the only option.)
Good plate was most often 'proofed' - the armor smith loading a pistol, taking ten steps back, then firing at the armor. The resulting spall was often decorated. The aror was 'bullet proofed'.
(Yes, that's where the phrase comes from.)
On the other hand, there is a reason chain went away - the links would be driven into the flesh, and the wounds were much more likely to become infected as a result. Though I seem to recall a Polish factory making the stuff until around 1910.
The most common armor in the Reformation/Counter-Reformation was a leather coat - it didn't do much to stop a bullet, but helped against things like the large splinters that would be thrown out when a bullet or cannon ball hit wood - the incidental damage from flying debris was actually a more common hazard than the ball itself.
If a soldier was going to wear anything more it was often a placart, a belly plate to prevent gut wounds - the most certain way to die in battle. Tassets were nice, but the gut was what worried folks.
So, I go with high damage, a x3 critical modifier, but don't use any special rules for ignoring armor - 'cause it doesn't.
The Auld Grump, who feels that guns and D&D get along just fine....
