The proposed use, i.e. sitting on a rooftop taking one shot by yourself at a target, is exactly "sniping". And not something you'd do with a 17th century musket.
Here is a manual on how to use a musket in the English Civil War. Standard practice was to have a line of people firing them all at once, then hopefully someone would hit something.
Awww.... You caught me!
What of gameplay value, though? The game engine does have a feature to aim at characters and shoot at them in 1st person mode. This feature used to be hidden and required a cheat to enable.
When I added ths functionality to the (very historically wrong, I know!) Shotgun Easter Egg, I spent some time working in the actual correct damage calculations based on your equipped pistol.
Before that it was overpowered on purpose just for fun, but now it deals damage and uses ammo the same way as using a normal gun does.
So then the question is: If no historical gun would ever have been used like that, should we choose for historical accuracy or gameplay?
In this case, we are proposing one scene where this feature is required in a storyline that isn't entirely accurate anyway.
Especially the Bartolomeu one, since that one also contains fantasy elements for variety's sake.
While the option to use this also exists during regular play when using a musket, of course the choice to do so lies with the players.
And I don't think anyone is even aware of its existence. So on that account, I reckon one "showcase" situation to let players know about it should not be that bad?
