In CBT, LRM were 1 Point of Damage per Missle and SRM were 2 points of Damage per Missle.
Then came the glorious invention of ATM. Which has 1 Point of Damage on E-LRM Reach, 2 Points of Damage on LRM reach and 3 Points of Damage in SRM Reach.
LRM comes in 5, 10, 15, 20.
SRM comes in 2, 4, 6
ATM comes in 3, 6, 9, 12
Basically, it's E-LRM and E-SRM in one.
MRM do one point of Damage per Missles, but are completely unguided.
MRM comes in 10, 20, 30, 40