To name an example: I was in a siege today. Enemy had a lot of levie inf, so there was a lot of shooting at first. My line infantry garrison ran out of bullets first (why do line infantry have less bullets than levie anyway?) so I checked their killcount. 304. With 300 men in the unit. Meaning every man killed 1 enemy. Using 10 bullets in the process. With a rifled weapon. That's just too few. Even if I wasn't playing Aizu I'd probably start recruiting more samurai and cavalry.
I personally think the best solution would be too put weapon effectiveness between where it is now and where it is in vanilla (and to buff the line inf ammo, but that's a different matter)
This would still make melee troops very strong, but this is countered by the decreased movement speed of Darthmod. This means that although riflemen are less accurate than in vanilla and will kill less per volley (thus making battles longer and giving more time to react before soldiers are shot to pieces) but approaching melee troops will be in enemy fire for a longer period of time.