This is where the bigest differences between the Napoleonic period or for that matter the most of the horse and musket period lie. There is first little or no volley fire as is represented in Sharpe Practice where the aim is to maximise the shock effect of fire in this period loading drill was more complex and less streamlined so rates of fire where lower than later and the emphasis was on keeping up a constant hail of fire and avoiding a situation where you could not fire at all. There where a lot of variations on the drills used more than one for most nations as they changed over the period but that said they boil down to one of two types Rotational Fire & Group Fire in the former each soldier loaded and fired very much in his own time after a possible initial "volley" though that might be missing if the weapons in use where matchlocks which though they where becoming increasingly rare as the period progressed where not always carried loaded, The firming line was formed. and the soldiers would start to load then. In some versions of the drill the soldier actually rotated through the ranks going back to reload and filtering forward to discharge his weapon. the advantages of this drill was that the line could be quite deep which was good for morale in a fire fight but the shock effect of the fire was diminished as it was spread out over time The firing line was also static whilst firing as to move it would disrupt the firing and be hard to do as it would be at all stages of the process of loading at any one time. In the latter the fire was coordinated and an attempt was made for groups within the firing line to fire simultaneously increasing the shock effect of the fire but still meaning that fire was continuous if delivered in sharp bursts as each group fired in turn.
All of this is modelled in Beneath the Lilly Banners so we can leave it alone, but for Sharp Practice we need to decide how to do this and I would suggest the following though I have not play tested them yet. Steve my gineapig requires painted toys to encourage him to partake of play testing. and I have only just broken my painting block.
For Rotational fire I would allow fire up to four ranks deep but roll half a dice per figure firing and halve the shock that results. I would also say for now that you only move or fire as shooting using a Rotational Drill takes both your actions.
For Group fire I would allow fire up to three ranks deep with half a dice per figure firing per action and only allow a movement action before a firing action for a firing line and even then I would have this cause problems as every thing I have read suggests that firing lines where hard to move
I will go of and try this and the other rules changes and report back but would welcome your input as I go along