M1 and Neo are 2 totally different guns. M1 has a clip size of 8 but has one of the longest reloads in the game. It does 8 damage but has a special ability to shoot through extremely thick walls vertically. (Can shoot through wood boxes vertically without damaging them) Be warned though. M1 cannot be repaired for some reason. I don't know what's in the admin's mind about not making m1 repairable. If you choose to get m1, use it while it lasts.
Steampunk is like an m4. (as mentioned in the post above me) Steampunk has good rate of fire, acceptable freeze rate (slightly more freeze than m4) but has a clip size of 20. Reload is average. Steampunk is good for new players who need a decent gun.