Out of curiosity of Napoleonic tactics in general, I’ve been reading diaries and books from soldiers who took part in the wars. I’ve read some from the French, British, and Russian perspective. In many of them, the soldiers casually talk about aiming in combat for the best effect.
Particularly I read the autobiography of Sergeant William Lawrence and he mentions not just personally aiming, but that on certain occasions his entire unit was instructed that when forming square to oppose cavalry, that they were to aim at the larger unarmored horses rather than the soldiers to achieve more deadly volleys. This isn’t some skirmish action where you’d expect marksman to be employed, these are battalion or higher level squares which would be predominantly, if not entirely, line troops. I’d also like to note that the unit leadership having to tell the soldiers to stop aiming at the riders indicates that telling them to aim at the horses isn’t some exception to the rule, but that previously it was common practice to aim in the first place.
Similarly on the French side, while I can’t recall specific examples of aiming in combat off the top of my head, I do recall that the Grand Armee had regular marksmanship competitions, which seems pretty silly to do if you didn’t expect your soldiers to aim in combat. This surprised me because another claim I’ve often read in books is that soldiers of the age very rarely received lived ammo training, much less training on marksmanship.
These are just two examples that come to mind. I’ve read many others that also mention marksmanship in combat.
And yes, I’m aware all nations employed light troops that were expected to perform aimed shots more deliberately, in both examples above they’re of or include regular line soldiers rather than just the lights.
The 1791 French drill manual instructs the soldier to look down the barrel of his musket before he fires. The 1815 American manual of Winfield Scott, mostly based on it , does the same: specifying even that he close his left eye, and "sink forward the head towards the butt in order to level". The French joue , for the command, is usually translated as "present", as opposed to the modern braque, for "aim" but whatever the word, the soldiers are looking down the barrels of their muskets at something they want to shoot. So, we can say they're aiming. Why not?
But the important thing, here, is : what do they expect to be able to hit? Most would have enough experience to know about how much a musket ball would drop at 50 or 100 yards, and so the officer commanding them to aim at the horses ( lower) and not the riders ( higher) is giving a practical command: that volley is likely to hit horses, as opposed to missing a number of riders.
I've not heard of regular marksmanship competitions in Napoleon's army ( would be glad to read about one). It's worth noting, however, that if a musket is loaded with a patched ball, and with a measured powder charge, it will shoot as accurately as a rifle up to around 100 yards. There was a sight on top of the front barrel band on the Charleville musket ( which was the model for the American one) and so, loading carefully, even without a rear sight a soldier likely could get a decent group on a large target doing that at 50 yards or so.
But if he loaded according to the manual, no. Some of the powder in the cartridge would go down the barrel, some in the pan for priming, so that powder charge would vary. The ball would be a loose fit in the bore, with the cartridge paper pushed down on top of it. Just like the load, those shots are not going to be very consistent.
It's also not quite true that recruits rarely received live ammo training. The procedure for loading of a musket was complex: if the recruit didn't go through the steps in the correct order- dropped the ball in before the powder, say- his musket might be disabled, would have to be brought to an officer who would be equipped and ready to pull the load ( and note the soldier for punishment later) . That meant that loading had to become as automatic as possible, deeply ingrained in the recruit's mind. If you look at the manuals linked above, they are very specific about where the hand grips the musket, placement of the feet, etc. There was no room for interpretation! But lots of time running through the drill without firing didn't mean they never fired in drill- just that they drilled a lot more than they fired.