Yes, hate me for this, but I just think it limit's me to much. I find it pretty unnessecary to carry a pistol with me, with all the other options for supressed ARs etc... I used to use the shorty and the small crossbow (what ever that thing is called) insted of the M-79 a lot. But I just don't like the thing taking up a pramary slot. I never found it actually op, just the ammount of ammo for it you can carry is pretty retarded, the ammount of ammo in this game (and FC3) in general is stupid. FC2 in infamous did such a better job.
I have no idea how to change it back to a secondary. I managed to get it to show up in the secondary tab in the shop, but that's it, the thing itself remains primary in dosen't even unlock then when i pick it up.