I'd say reduce movement in a move and fire order. 4" sounds good, 3" is just as well. However, if you reduce the movement too much, the game might get bogged down a little. Note that if you play move and shoot, your troops WILL shoot. For slow reloading weapons (muskets) that means next phase no shooting. The shooting shouldn't be optional in move and shoot. Even if you cannot see an enemy or the enemy troops are too far away, your soldiers at least try to hit something (shooting at the boogie-man in thebushes or whatever). Anyway, a wasted shot if there is nothing to hit.