Why are there magazine-fed machine guns?

Factual Questions
1

Modern machine guns come in all shapes and sizes, from squad weapons to general purpose to big vehicle mounted nasties.

The popular conception of a machine gun is a belt or drum-fed weapon-- 100 or more rounds attached.

Yet. . . there are still squad weapons like the RPK, which typically uses a 40-round magazine.

What’s the point of a 40-round machine gun? I’m assuming that, in general, machine guns will have more stopping power, range, durability/ability to sustain a high rate of fire, and of course, a high rate of fire. But it’s that last bit that confuses me-- what’s the point of having a high rate of fire when you’re only using 40 rounds? Why not just carry assault rifles instead?

Is this just a case of flexibility, i.e. the RPK is engineered to use the same magazine as the AK series in the event it needs to, but there’s no particular benefit to doing so?

2

I am not a weapons expert, but if your machine gun was only belt fed, that could be a limitation on the battlefield - if it can also take a magazine then you could always have ammo from someone that was not a machine gunner.

So, interchangeability with the other weapons on the battlefield.

3

Politics.

Seldom are decisions made where politics doesn’t play a role.

4

Logistics. It takes more to support the supply of belted ammunition. Either you have non-decentegrating belts which need to be re-used and properly maintained. Plus, it takes additional equipment to load the ammunition into the links.

There are decentegrating links like the United States uses. Technically, one could re-use them and rebelt ammunition, but it takes fucking forever! It would be much faster to simply load them in to a magazine.

With the RPK in your example, it is much simpler and much cheaper for the soldiers to load normal rounds into magazines. The magazines can be changed quickly enough that the added logistical simplicity outweighs the inherent disadvantages of small magazines.
There are larger drums, as well. These can be loaded without special equipment and they are easy to maintain than belts.

5

In battle, belt-fed machine guns obviously have a lot more ammo to use. However, they usually are used in fixed positions, sometimes taking one person to feed the belt into the weapon. Even if not, it usually is on a tripod or bipod, and therefore not all that mobile.

A hundred years or so ago, I was a light-weapons specialist and the weapon I used was a BAR (Browning Automatic Rifle), which I truly loved. Sort of half way between a machine gun and a rifle. Too heavy and long to fire from the shoulder, but it had a little bipod, so dropping to the ground, it was immediately ready for use. And, if necessary, one could pick it up and skedaddle the hell out of there.

Magazine-fed guns are obviously much, much more portable, and my guess is they may be used more by police than in the army today, but I don’t know. As far as I do know, the old Thompson Machine gun, with a round magazine, was one of the earliest hand-held machine guns.

Anyway, in the Army way back then, it was emphasized that with any automatic weapon, we should not spray the entire area, as in every Hollywood picture you will see, but AIM carefully and squeeze off a couple of rounds, aim again, and so forth. Otherwise you will quickly run out of ammo, the weapon will get way too hot, and possibly be damaged. In WWII, there was a small .45 cal machine we called a “grease gun” because that is what it looked like. It was designed to be very effective in house-to-house combat; stick the muzzle of that sucker in a door, and spray shots all over. Anybody hit by a .45 slug is likely to be put out of action.

BTW, there used to be heavy duty machine guns in the army that were water-cooled. Doubt if such are used today, but who knows?

6

I believe that while they use that tactic, they also do combine it with the WW2-style use of a good burst of bullets to force defenders into cover, while riflemen pick off individual targets. Any more recent soldiers care to share?

7

Although this has essentially been stated, let me make it clear: a belt-fed machinegun is a crew-serviced weapon. It requires at least two (a gunner and loader, and depending on the weapon, perhaps a third) people to operate it. A magazine-fed weapon only requires one person. So light machineguns like the BAR or the MG4, that are not too heavy to be practically carried by one gunner, may be fed from or have provisions for a box magazine. The Bren, which should have been considered a true medium machine gun by weight, was exclusively fed from curved box magazines that caused no end of trouble.

Stranger

8

Do tell. I read an article several years ago praising the Bren whose top-feeding magazines, like the Austens, were very reliable.

Also, is the M249 considered to be crew-served?

Thanks,
Rob

9

I can only reiterate what I’ve been told by veterans and info I’ve read, as I’ve never fired the Bren, but it was standard practice to download the magazines and discard them as soon as unused magazines became available as the poor quality control on heat treatment of the boxes and springs made them prone to damage and fatigue. The gun itself was supposedly reasonably reliable as long as it was kept clean and well-serviced.

The M249 is a squad automatic weapon (SAW) intended to be used by one person from either a standing position or firing crouched or prone from a bipod. However, the weight of the standard ammunition load-out would require another soldier to carry over any distance. More often, it is deployed by mechanized infantry or airborne assault role to an essentially fixed position.

Stranger

10

I am a medic, not an infantryman, but I think that Stanger’s description of the M249 applies to an M240B (the heavy 7.62 version of the 249). From what I have seen and been taught the M249 is carried along with its ammo by one person and used to provide highly mobile suppressive fire.

Most 249s in the army today have shortened barrels and stocks and are not a whole lot heavier than and M16, definitely manageable by one average soldier for the duration of a mission.

11

Correct.

Also, I might point out, box magazines cause frequent jams because the magazine springs are not always strong enough to keep up with the M-249’s high rate of fire.

So, while the M-249 has the capability of using M-16 magazines, this would only be done in an emergency, when one has run out of 200-round ammo belts. I have found that just inserting the magazine is usually not sufficient. A solid whack with the heel of one’s left hand helps get things started.

The RPK usually uses 75-round drum magazines. It can also use AK-type box magazines, which are usually 30 rounds, because the 40-round ones are too long and prevent firing from the prone position.

For more info on Squad Automatic Weapons, see my website.

12

Disclaimer – I’ve never been in the armed services.

And what AmunRa has said.

Just from cruising WIKI,

I would suspect that the extended barrel also gives it an increased range.

And the M249 –

I would guess that a unit may carry extra M27 linked belt ammo that they could pass on to the machine gunner as they try to move forward or flank the enemy. Seems like a good idea to have a few carry a bit more ammo specifically designed for the weapon (IMHO, I have no idea if this is how a squad/unit operates). As such it is not a crew served weapon in that two or three combatants must service it as it is operating.

And, at least/last, it could feed from standard magazines. Allowing the machine gunner to move if he has to, and still have a weapon.

13

Hey, thanks everybody for the comments/learnin’.

It just always seemed to me to be kind of pointless to carry around a “machine gun” that only carried as much ammunition as your standard assault rifle. If the purpose of an MG is suppressive fire, then wouldn’t ammo load be the primary concern? If all I want to do is shoot 30 rounds off fast to make the bad guys duck, any ol’ assault rifle (well, fully-auto capable assault rifle) can do that, why bother with a different weapon in the squad?