Considering how many times and places I’ve read that “spray and pray” is NOT a smart move, it begs the question of just when it is. Obviously submachine guns and full-auto assault rifles continue to be made and carried by various forces all over the world. So they must fullfil a combat niche that can’t be met by single round at a time weapons. What is the doctrine on full-auto fire?
I am not a soldier or a SWAT team member but my father was a gun dealer and we had some fully automatic machine guns when I was growing up. IIRC, our UZI would shoot nine 9mm rounds a second and the Mach 10 would shoot nineteen .45 rounds a second. With a 50 round clip, you would burn through ammo very fast, too fast in my mind if you held the trigger. I always thought of the fully auto mode as a novelty and pretty useless. I suppose if you were in a confined space with someone approaching you, it could be useful to sweep the area and ensure a hit. Randomly firing in full auto mode in a semi-open area just seems like it would waste a lot of ammo. I can understand large belt-fed machine guns much better.
I was in the Marines right after VN, and my M16 only had semi auto and auto. We were taught to fire in short bursts unless we were involved in coordinated suppressive fire. In small unit tactics, e.g. fire teams (4 Marines head by a Lance Corporal or Corporal) or squad (four fire teams, headed by a Sergeant, which also might have a machine and or mortar assigned to the squad), that is just the kind of thing you drill. it is especially important to drill this in case of retreat to keep the attacking enemy from catching up or taking positions on you, so you get into defensive position from which to resume the attack.
in the attack, which is usually better planned than a retreat, your platoon automatic weapons are employed. Each squad might have a squad automatic weapon assigned (we actually had reconfiguired M-14’s with pistol grips and bigger shoulder stock, so they worked something like the old BAR) or a heavy machine gun (M-60) assigned from weapons platoon. Attacks are usually planned at the company level, so the CO would assign resources from the Weapons Platoon, the fourth platoon in your typical Marine rifle company of three rifle platoons and one weapons platoon (heavy machine guns, mortars, anti tank weapons, etc.)
You don’t want to be firing you rifle on full auto in the attack because you will waste ammo, unless you are really closing in for the kill.
My son who served as Marine recently had an M-16 type weapon called an M-4 that had semi auto, burst, but no full auto. The squad automatic weapon is similar to an M16 but could fire belt ammo – the M-249 (I got to fire one when I visited my son’s ship when they returned from Afghanistan.) way better than a modified M14 or BAR, lighter than the M-60.
when he went to Iraq he got an M-4A1 that fired semi, burst and auto but told me that even in close quarters fighting he left it on burst.
Shock and Awe. Or just when you are scared shitless and lose control.
From what i have read there used to be a tactic in Vietnam called the mad minute, your heading up a road and you get ambushed so all troopers fire on full rock and roll and then advance into the path of the ambush to kill whom ever is firing on em.
Some of the Iraqi veterans that I have heard now call this Death Blossom.
Declan
Close quarters combat (like, clearing buildings), VIP protection, when in ambush or when ambushing someone. Basically in situations when enemy is very close to you and you want him to be dead right now and for sure - you just empty your magazine into him and reload.
Second situation is suppression fire, but it works better in coordinated effort of whole squad.
Also, there is much use for heavier, belt-fed full-auto weapons. Suppression fire, mowing down poor guys storming your positions, shooting at light aircrafts and UAVS, perforating unarmored vehicles, “softening” enemy positions before final assault etc.
I am not infantry, but am prior USAF RED HORSE, and because our construction sites were expected to be self sufficient, we were taught some basic base/perimeter defense. (For this discussion, assume ‘Camp Two by Four’ is in the middle of nowhere, with a concertina wire perimeter fence).
At any given time, Camp 2x4 has assigned sentries, with a couple of automatic weapons assigned to the perimeter. In a final, “Oh shit, they’re coming through the wire” call, each automatic weapon was assigned a direction (or usually a visual target–“Shoot towards that tree there!”) to interlock fire with the weapon adjacent to it. On that call, the weapon fires in that particular assigned direction until A) you ran out of ammo (in which case you send your assistant to go get more), B) your barrel literally melted down, or C) your gun crew was dead.
Cross your index fingers of both hands: that’s how interlocking fire was supposed to work. It is meant to provide another physical barrier (a wall of flying lead) between you and the enemy. Anyone trying to get any closer would be shot up pretty good. Obviously you can’t rock-and-roll too long, so the call is usually a last-resort thing, or has to be very well timed.
But that’s the most extreme case I can think of: The movie “We Were Soldiers” involves a few scenes in the Ia Drang valley where an entire NVA division was descending out of the mountains onto a battalion-sized landing zone in the bottom of the valley. But, you get the drift. . .
Tripler
Yes, we called it “Camp 2x4”. There was also “Camp Spackle”, “Camp Rafter”, and “Camp Sheetrock”.
Indeed, according to my reading of field manuals, that is the tactic the US Military uses in dealing with an ambush… bring our generally superior rate of fire to bear on the ambush point, and rush.
This serves to disrupt the ambush, and puts the former aggressor on the defensive.
I am amused by the progression of slang though… from whatever was used in the 70’s, we now have a “Last Starfighter” reference. Awesome!
The “Mad Minute” is an old British tactic dating back to the days of the Boer War; it involves firing your Lee-Enfield as fast as you possibly can at aimed targets (ie, picking a particular target, aiming for effect, and unloading on it as fast as you can work the bolt.) The record is 36 aimed rounds fired in one minute- that’s 36 rounds that were aimed and put into a man-sized target at 100 yards in 1 minute. Including reloading. From a bolt-action rifle with a 10 round magazine.
It’s no surprise the Germans thought they were encountering machine-guns in the early days of WWI when they came up against battalions of British soldiers armed with SMLE rifles…
As for full-auto weapons, they do have their uses (on things like aircraft, tanks, and armoured personnel carriers), and if I was in the military operating in an urban or close-range environment I’d insist on carrying a Thompson M1928A1 SMG, with a 50-round drum magazine and forward pistol grip. They fire a heavy cartridge at a relatively low RPM, and have almost no appreciable recoil IMHO because of the weight. Yes, they’re heavy, but to quote Boris from Snatch: “Heavy is good. Heavy is reliable. If it does not work, you can always hit him with it.” 
Another reason full auto is wasteful in lighter weaponry (say, lighter than a mounted .50cal) is because it is innacurate. There is a noticeable tendency when firing an automatic weapon for the barrel to rise due to recoil and you have to keep correcting against it.
In my military experience we only used it as suppression fire or to cover a retreat (automatic weapons firing makes your unit seem bigger than it is, with more weapons than it really has).
But (and I think I read this in Quartered Safe Out Here, George MacDonald Fraser) a weapon that doesn’t do this isn’t necessarily a good thing. I think it was the Bren gun that was quoted as such a straight shooter that if you just left it on one target and kept the trigger down it would empty the whole magazine into basically the same spot - whereas a gun that “crept” across the target would more or less saw it in half for no added effort. I have never shot any automatic weapon, so take this for the very little that it is worth. 
Yes and no. Bren indeed was famous for it’s accuracy, but it’s not bad thing. You know, to accurate gun can be made less accurate by slightly moving it. Too inaccurate weapon can’t be made more accurate.
And from what I have heard and read, when the term was used in Vietnam, it meant that everyone in the base shot at the trees on the perimeter for a minute or so.
The NVA liked to attack at night, so around dusk, the base would have a mad minute and blast the heck out of the surrounding jungle in order to surprise the enemy (if there was one there) and possibly break up any attack that might be in the works.
The counter-ambush information is correct, I’ve just never heard the term “mad minute” used in that way.
It’s just a damn shame you guys never actually built anything.
Chefguy - former Seabee
We have all doubtless heard of soldiers or police being ordered to fire into large crowds of civilians who are unarmed, or armed with only non-firearms. I always assumed that this was done using automatic weaponry, since an angry mob could probably overpower soldiers who were firing only one shot at a time. So I suppose this is an effective combat tactic, if you want to hold your ground at the expense of causing a massacre.
It’s useful for drive by shootings and action movies.
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The basic Marine rifle squad has, to the best of my knowledge, remained at 13 men since near the end of WWII. It consists of three fire teams including the team leader, automatic rifleman and two riflemen/ammo bearers plus a grenadier.
Firing on full auto means firing 3 to 5 round bursts. Consistently firing more than that will burn out the barrel in very short order. Standard interlocking defensive fire means placing an automatic weapon on each flank and a third in the center, each instructed to cover a field slightly overlapping the other. The remaining riflemen in between picking targets of opportunity within their assigned field of fire. The grenadier being directed to targets selected by the squad leader, or by obvious necessity.
I retired over 29 years ago, but I believe the basic squad formation is still in use today.
Not sure what the Army uses today, but I was in during the transition from the M-16/A1 to the M-16/A2, the main difference being that full automatic didn’t exist in the M2 – only three round burst.
Having looked at the firing mechanisms of both, it astounds me that there aren’t a lot of street modified automatic weapons. It’s trivial to adapt the M2 to fully automatic. I seem to recall that I believed I’d be able to convert the semi-automatic to full automatic, and leave the three round burst alone as the simplest option.
During basic with the M1’s, we used full automatic to get rid of the extra blank rounds. This was during earlier training before using live ammo. I was on the detail told to get rid of it, so we seriously overheated (and dirtied!) our weapons getting rid of the rounds over ammo boxes to collect the brass.