I have done military service, but it was a long time ago and I have never heard a shot fired in anger. We used
Heckler & Koch G3A3 battle rifle, which can fire in either semi-automatic or fully automatic mode. As far as I can remember we were trained to mainly use semi-automatic mode, and possibly we used burst for suppressive fire. Anyhow, what I remember or not is of less importance since it was a long time ago and I was an army engineer, so we were better at building bridges and blowing stuff up than firing our rifles.
My question to all veterans is: Based upon your experience, in what situations do you use your rifle to fire burst/full auto instead of single shots?
I'd have to say
Situation 1: Firing at targets you're pretty sure are there but you can't see, like you hear an enemy or see a muzzle flash in nearby vegetation/foliage. It's for firing as many rounds as you can into the suspicious foliage before ducking back behind cover yourself.
Situation 2: Clearing rooms, trenches, bunkers, (like sticking the barrel of the rifle around the corner and hosing down the room to kill, incapacitate, and stun the enemy before teammates clear it with semiauto or burst fire tactics) and vehicles (like sticking the barrel of your rifle into an open vehicle hatch and expending all ammo to kill the crewmen who might be operating vehicle weapons.
Situation 3: You're facing an assault rush at close range and you have enough time to empty your magazine and reload for the close quarters fighting. If you don't have the time, then rapid semiauto fire so you have some ammo left when they reach your position. Related to this is final protective fires against assault rushes or human wave attacks where you need to fire as much ammo as you can at the enemy from the flank as they rush your positions. For anyone who doesn't know, final protective fires is a tactic where you stop shooting at the enemy to the front and start firing across the front of your own positions to catch the enemy in the flank. It's for when your position is getting overrun, and each squad or position is covering the one to its side, in a triangle or rectangle formation. This is more of a machinegun tactic I guess, but if your element is armed with rifles it's better than nothing.
Situation 4: You're trying to drive off an angry mob that is unarmed. The full auto fire is to threaten them and get them to withdraw before you light them up. Rapid semiauto or a couple of bursts are good choices, but full auto over a mob's head on in front of their feet is more frightening and lets them know that the gloves are
off.
For suppressive fire with a rifle, IMO it would be better to use rapid semiauto fire than full auto. Full auto or even burst firing over and over would burn up a magazine in about 2 seconds and require reloading, which would give the enemy time to return fire instead of keeping him suppressed. Steady rapid semiauto fire would suppress the enemy longer before you need to reload.
When using something like an M249 Squad Automatic Weapon, we were trained to use controlled bursts to minimize stoppages and barrel overheating. Its 200 round belt allowed sustained suppressive fire using bursts. GPMG's like the M60 and the M240B are of course built for sustained full auto firing for suppression, final protective fires, or blazing away at numerous targets in the open.
Just my opinions.