When the price of ammo started on up, I installed a 3 round burst on my M16 for machine gun shoots. I thought giving the public a burst would satisfy their latent Rambo tedencies. Didn't work. Pull the trigger six times and they'd dump the 18 I loaded. To answer the original question...on burst, snap the trigger for one round, the next time you fire, two will go off. Snap off two, your next pull one goes off. Its a ratchet set up. Real #!@%^ to install. You can still lay down a field of fire if you got rythm.
