New sounds for M4. This is MK18 sounds. Replace your default M4 sounds. And M4 data lines :

$ M4 INSTANT_HIT 130.0 120.0 356 -1 5 riflebad 50 30 0.74 -0.04 0.13 0 0 0.45 0.9 6 9 7 6 9 6 99 7001
$ M4 INSTANT_HIT 145.0 190.0 356 -1 5 rifle 50 30 0.74 -0.04 0.13 1 200 0.65 1.0 6 8 6 6 8 6 99 7011
$ M4 INSTANT_HIT 250.0 390.0 356 -1 5 rifle 50 60 0.74 -0.04 0.13 2 999 0.80 1.1 6 8 6 6 8 6 99 7031

Enjoy :)