So, 80 damage from a musket shot is what you'd call low damage?
I mean, let's subtract effective armour from that, since this is pierce damage. Pierce damage tend to ignore about half of armour, so with the standard 23 armour clothing we can estimate that damage is about 67 to the body on an average hit.
But there are other factors, such as whether the target is moving towards you or you towards him which has some effect, then there's distance traveled to target which does in fact have an effect on warband projectile damage.
So assuming that both the firer and the target are standing still, and that the hit is point blank with an 80 damage musket, and the target has 20-25 armour, there will be a damage result of about 65-70 to the body.
Base health is 35 HP with 0 STR and 0 Ironflesh, so the minimum of 65 HP requires either 30 STR alone, or 10 IF and 10 STR, or as the player who intends to get shot may build his character, 18STR and 6 Ironflesh.
With this you can survive a single musket shot, assuming it doesn't hit you in the head in which case you have no chance at all without cheating or using decreased damage.
So the only guys I expect might not die to a standard musket shot are Curassiers of French or Austrian variety, or a very lucky elite Grenadier.
Muskets kill in one hit with 80 damage every target who would be expected to go down in a hit.
The average STR for most AI units is around 10.
That's 45 HP assuming no Ironflesh. This target will likely die to a single pistol shot according to the rules above, and that's often what I see play out in fact when I shoot a highwayman.
All this seems pretty fair to me. The fact that I have to lower the difficulty to not die every single time I get shot is reason enough for me to suspect that ranged damage is more than high enough.
Finally, large caliber ball ammunition is not quite the deathray you seem to think it is.
Shot placement is everything and always has been. You shoot a man in the arm with a lead ball and... now he has a hole in his arm the size of that lead ball. It doesn't necessarily kill him.
The same can be said of bodyshots which do not strike vital organs.
Now the man has two options. He can seek medical attention or he can keep fighting with his wounds, as men often did.
People do not seem to understand that a standard ball round of any type, modern or otherwise is nothing more than a small piece of metal going very fast. It will often go straight through a man if it doesn't slow down fast enough, and even if it does stop, lead balls do not deform or fragment usually unless they strike bone.
It's no different from a smoothbore shotgun slug. One simply has more modern manufacturing techniques and more consistent powder charges for more accurate shot groupings.
Hit the brain stem or brain and you have instant death.
Hit the heart, lungs, or liver and you've got a definite fast kill.
Hit the spinal column and you have incapacitation.
Hit a large blood vessel and you have a fast and probably mortal wound, but not necessarily incapacitation.
