MG42 question

[SSN Vet]

Recently streaming an episode of Lee Emry's Lock And Load show, I learned that the secret to the air cooled MG42's performance was that it had a very quick and easy barrel change mechanism and that the crew would change barrels quite frequently.

Does anybody know whether these barrels were still serviceable after use?

or did they get trashed?

If serviceable, would they go straight back into rotation after cooling down?

or would they require cleaning?

Inquiring minds want to know

 

[Jeff White]

Of course they are still serviceable (or should be if the crew is properly trained) and yes they were changed back after they cooled. This kept a gun in operation.

Most machine guns are issued with two barrels so they can stay in continuous operation if necessary.

 

[SSN Vet]

I'm wondering at what round count they would consider a barrel "shot out" and whether the crews had bore gauges to use.

 

[Sam1911]

Here's how it goes on a 240:

 

[Jeff White]

I don't know what the Wehrmacht issued, but in the US Army, barrel erosion and serviceability gaging is done at the direct support maintenance level. Machine gun crews and even unit armorers are not issued the gages to check the barrels.

 

[Billy Shears]

I'm wondering at what round count they would consider a barrel "shot out" and whether the crews had bore gauges to use.

If the barrel was changed at proper intervals, and not allowed to get overheated, it should have been good for tens of thousands of rounds. Continued firing of a heated barrel would shorten that, of course.

Cleaning would normally be done as soon after a combat action as possible, along with the rest of the unit's weapons, especially as corrosive ammo was used in WWII, and you wouldn't want to go too long without cleaning out the barrels. But a barrel, after it had cooled enough, would be put right back on the gun and reused as long as the gun was still in combat. I believe I read that the MG42 crews carried two spares.

 

[CapnMac]

Wehrmacht was a bit unique. When they rebuilt in the '30s they fundamentally changed their infantry structure. Instead of rifle companies with supporting weapon squads/platoons, they changed to a maniple of 2 MGs with an a loader and three riflemen each. In effect, the riflemen supported the MG and AG (this was handy for packing all the ammo needed, too--which is why there are so many photos of truppen with a Kar 98k in one hand and an ammo can in the other).

One of the badges of status the a-gunner had was carrying the spare barrel carrier, as each MG was sent to the field with three barrels. This even with the less-easy to change MG 34.

In the fixed/heavy MG role, one of the riflemen was the assistant a-gunner--he got to hump the Layfayette tripon (and rifle and box of ammo). Once up on the tripod, the a-gunner passed ammo from the left and the a-a gunner was on the right to pluck the hot barrel out with an asbestos mitt, and get the new one seated.

 

[Malamute]

They are still being used by the German and other armies. The current designation is MG-3.

https://www.youtube.com/watch?v=AaNFO5WfIS4

https://www.youtube.com/watch?v=TAxkvctd5Ps

Looks like the perfect thing to have in hand when coming around a corner and finding the street blocked by hoards of ISIS guys.

Germany gave some MG-3's and other small arms to the Kurdish fighters recently.

 

[Jeff White]

The M60 (how I hated that abomination) was supposed to be the US Army's answer to the MG42. Instead of just copying it, we used parts of it and parts of other machine guns and created a piece of junk.

I have been told by people who used them when they were new that they weren't so bad. But by the time I went in the Army in 1974 they were pretty well worn out. But they soldiered on until about 2004 in some units. At the end of it's career it earned the distinction of being the only weapon in the inventory that you could order the receiver as a replacement part.

 

[Sarge]

I got my first MG 42 in 1961(I still have it). Having had 4 in the years since, I'm now back to one.
I would take the 42/MG1/MG3 over anything else out there!
I am very familiar with the M60, having used one in combat. While it is an OK weapon I'd take the 42 family over the 60 in a heart beat!
Sarge

 

[Jim K]

The MG1, MG2 and MG3 were all in 7.62 NATO and basically all the same gun. The MG2 was the MG42 converted to 7.62.

Jim

 

[mljdeckard]

It's only if you DON'T switch it out when it needs it you have a problem.

We burned up an M-2 barrel in Germany. It went discolored, we had to turn it in.

 

[Jenrick]

The barrel change is based more on heat then wear in the field. If it gets too hot the dispersion opens up beyond acceptable limits, and there is also the risk of the ammo cooking off in the chamber potentially leading to a runaway gun. Water cooled guns from WW1 could, and frequently were, fired for LONG (several hours) periods of time. Basically so long as the water and the ammo held out they would be fired pretty much indefinitely.

There are both rate of fire (RoF) and time of fire recommendations on when to change a barrel. For instance rapid fire might be a burst of 6-10 rounds (RoF) every 10-15 seconds. After 3 minutes of rapid fire the Field Manual (FM) might call for a barrel change. Full cyclic (holding the trigger down) might call for a barrel change after 1 minute. Different guns, different ammo, etc all dictate when a barrel change should be made.

As CapnMac discussed, the Wehrmacht was different the US Army in that they felt the MG was the primary killing arm. Their MG's tended to have a much lower dispersion then American MG's, and a much higher RoF. The goal was to place a killing burst on a given target, even if it was rapidly moving or fleetingly appearing between cover. American MG's had a much higher dispersion and much lower RoF, they were designed to fix and pin an enemy. Against enemies in the open they were just as deadly as anyone else's MG's, but against a single rapidly moving point target they weren't as effective in killing/wounding. They could however put fire down on a larger easier much more efficiently, and for a far longer period of time with a given supply of ammunition compare to the MG34/MG42.

The MG42 would heat up faster due to the higher rate of fire then say the M1919 MG when firing a given quantity of ammunition, and it would be capable of firing it far faster than the M1919 (approximately double the cyclic rate). This would lead to a loss of acceptable accuracy, as such it would require more frequent barrel changes then the M1919, but this was offset by the ease (comparatively) with which it was done on the MG42.

The MG42 spare barrel case was actually designed to help cool the hot barrel while it was out of rotation. The barrels were not cleaned until after an engagement was over typically. There was no real reason to clean the barrel before putting it back into action.

-Jenrick

 

[Piper106]

the Wehrmacht was different the US Army in that they felt the MG was the primary killing arm. Their MG's tended to have a much lower dispersion then American MG's

I saw on the internet a WW2 vintage US Army training film on the subject of the MG 42, that showed the dispersion of the German MG 42 was higher than the US M1919. Which is correct on dispersion, or was it another apples to oranges comparison???

 

[Jenrick]

Remember WW2 training films were not exactly factual about all their claims. The Army produced a training film basically telling GI's the MG42 wasn't that dangerous and that they just had to wait for the belt to run out or the barrel to need a change and then they could assault it. While the later part is correct, the MG42 was devastatingly lethal. If you're referring to the training film I think your are, it's basically a giant propaganda piece for GI's in training to help bolster their confidence before they went overseas. It's certainly possible that the examples they "tested" were in fact less accurate than the American weapons selected for the "test." Without a lot more detail on the testing process it's very difficult to say this is valid.

I will say the M1917 water cooled MG they used, did legitimately have a reputation for accuracy. It is however an apples to oranges comparison to the have a water cooled MG in the test. A M1919 on a tripod would have been a much better comparison.

-Jenrick

 

[carsten1911]

4 seconds...

...is about the time an average trained MG3 / MG42-crew has to interrupt the firing....not too much time for an assault for sure.
Better training results in faster barrel change times. but I dont think any MG-team can do it faster than 2 seconds.

(operation of barrel change is just the same with both MGs)

The rule of thumb was 200 rounds (some say 300 rounds) before a barrel change. With the cadence of 1200 rpm this means roughly ten seconds of constant fire, then change.

Doing the math you see why the advice to do only short bursts with the MG3/ 42 is reasonable.

Carsten

 

[Sarge]

Bbl change was more commonly every can of ammo = 250 rds. The gunner changed the bbl while the assistant was loading a new belt. This from several Wehrmacht veterans I have talked to, including one who was a MG 42 gunner.
Sarge

 

[45_auto]

there is also the risk of the ammo cooking off in the chamber potentially leading to a runaway gun.

How would ammo cooking off in the chamber lead to a runaway gun in an open bolt weapon?

There's no round in the chamber until the trigger is pulled. And unless there is a mechanical failure of the trigger mechanism, letting go of the trigger locks the bolt back without loading the next round into the chamber.

On something like an MG42 running at 1200 rounds/second, each round only spends a total (stripping from belt, chambering, firing, and extracting) of 5/100 of a second in the chamber. Not nearly enough time to cook off even if the barrel was red hot.

I can see how an MG42 jammed with a round in the chamber could cook off a single shot, but how could it load the next round and run away unless the trigger is pulled?

I saw several m60's run away back in the early 1970's due to worn or damaged sears, but have never even heard of an open bolt weapon running away due to cooking off.

 

[Jenrick]

I was speaking generally, not directly about the MG42.

I'd have to check my copy of Herbert McBrides a Rifleman Went to War, but I believe he references this occurring with one of the early Colt MG's in WW1.

-Jenrick

 

[Jeff White]

I don't know how an open bolt gun could cook off since the ammo doesn't go into the chamber until it's fired.

If it was so hot that it would cook off when it hit the receiver it would detonate out of battery injuring the crew and probably destroying the gun.

 

[Jenrick]

I did some re-reading and yes the MG in question was a Colt M1895 MG (commonly know as a potato digger). It is closed bolt belt fed MG, and it is probably one of the reasons no one really makes a closed bolt belt fed MG anymore too.

-Jenrick