Damage increase varies with M (variable value) (M10 skill damage X5) (M1 one shot N damage M10 one shot NX5 damage)
Ammunition ceiling is reduced or ammunition consumption is faster (M1 one shot N ammunition M10 one shot NX5-10 ammunition)
BOSS attack mode more
The overall trend is that M1-M10 controls the combat rhythm (M1 bullets are more tolerant of higher errors)
M10 hits more accurately