Rifle, being accurate enough to pick the guys off their saddles, i guess need more practice.
Usually on moving targets consider relative speed and distance of target.
First for how much you swing forward shooting them and the distance for judging how high you would have to aim.
Also distance affects to the swing calculation. i.e.: a mounted guy moving at 100 yards
will not require the same forward swing than other moving at same speed at 25 yards, last probably swing next to none.
Other factor is the relative angle to you , and the relative direction he's going to.
A closing mounted guy will take less swing than a going away target, as the thing is,
you have to calculate where to bullet would be when you shoot, and where the target would be at the moment the bullet crosses its path.
All of this sounds difficult but once you get the feeling becomes easier.
In a normal battle try to kill unmounted targets, walking perpendicular or so (this is 90º, across of you), and you'll start to see the difference between far and near and the angle issue as well.
In homestead quick battle, which i like a lot, usually try to get two of the mounted guys first, as they're
getting near angle is not difficult, just aim higher, well above their heads and sure you can saddle one off.
Simulation of bullets, though a bit fast to my taste, is admirably well done
*Horses are easier to hit than riders.
*Not always the guy from the back comes in.
*Sometimes somehow they come from behind over the wall
*Usually when horses passed the front entrance , I go up stairs and check if there are anyone at the back door and shoot him in the face
*Knife may seem crap enough but faster than their blades.
*Also you have the long arm of a broom, use it
* From time to time , once horses passed, run to the nearest body and check, sometimes you'll find marvelous things
Uncannily enough, once I played "the man with no name" quick battle and AFTER the homestead scene,
farmer appears with Clint gun and skills ! That makes it much easier.
I reported it as a bug before.