Well there is a big difference between the m79 in public servers and the one in private servers (scrims).
The m79 users in public servers bascially have a buffet because you got like 8 on a team and there a limitless opponents to hit.
In a scrim however, with 2 going main, and 1 alt, the nades and spray counter any m79 shots. The only real use for m79 in a scrim is to push your way into enemy base. Otherwise it is a pretty useless gun (unless u dual wep).
Theres my 2 cents