its either delay both or un-delay barrett.
The barret has far more speed, the best range of any weapon, and the ability to sail across the map taking out up to three people. The M79 is not equal to the Barret in any way, shape, or form. It doesn't even have a 100% guaranteed kill that the Barret has.
I still don't think delay is the answer, but I guess with a little practice it could be overcome just as the delay is with Barret users. (Barret doesn't even have delay really since you can just hold down the button during the reload phase and get an instant shot
.) Even with a delay, you'd still get the kamikaze style M79ers running around smacking into the enemy due to having enough from to compensate from the time the enemy is spotted to impact, or due to the Barret (and possibly LAW?) delay bug if kept. It'd likely cut down the number of users which would be great, but it'd definitely would make the weapon less fun. I'd still rather just see increased splash damage for guaranteed selfkill point blank shots. Maybe the game could increase the respawn timer for selfkills as well, which would clear all those kamikaze M79ers littering the maps.