now in GTA San Andreas the M16 has an underbarrel grenade launcher, just don't stand too close to the object you're going to shoot at, after all the explosion after the shot will be such that it can easily overwhelm you too especially since it works in 2 modes 1st mode is the grenade mode (best used for combat against helicopters) 2nd mode is rocket mode (best used in battles on flat ground)
to activate the script in the 1st mode G+R, to activate the script in the 2nd mode M+I, to disable the script N+O to shoot, use the sight + look back, that is, first aim, and to shoot, click on the wheel