Did a search for this but didn't find anything.
First let me say that I am a new VCS player, but not new to the GTA franchise. I first starting playing VC [PC] several years ago, then went to SA [PC].
Anyway, I haven't gotten very far yet, but wanted to share this.
After you complete the intro mission, but before doing anything else, you can kill a few of your army "buddies" and get their M16's (or M4's). Once your wanted level gets to 3 stars or so, go back into your barracks, collect the pistol, save the game, re-load, and repeat as many times as necessary to max out the ammo on the rifle and pistol, plus you get full health back and your wanted level is cleared.
You could also collect the pistol before saving and when you re-load the save it will have reappeared.
My apologies if I am posting something already known.