Machine Gun RPM Discussion

[Tony Williams]

The neat trick is that the Sherman coax used the same mounting points as the ground M1919 .30cal and M2 .50cal.

If your tank crew wanted a .50cal coax, you needed to acquire a .50 from somewhere (as simple as the AA pintle if you're a US tank) and then pull out the M1919 coax. The whole swap took about as long as putting either M1919 or M2 onto a tripod.

British Army coax guns and ammo were a mess. First you have the Vickers in .303 inch, then they chose the Besa in 7.9mm as a replacement, and finally they acquired the Browning in .30 US. Three different weapons using three non-interchangeable types of ammo. At the same time the RAF were using the Browning in .303. The RAF version is interesting because the gun design was modified so that it fired from an open bolt, thereby avoiding the the problem of cook-offs caused by overheating the breech. This would have been useful to have anyway.

With the benefit of hindsight they could have avoided all this by adopting the Browning in open-bolt form but with a much heavier barrel and a reduced rate of fire. Then when US AFVs came along, it would be a simple matter to swap out the .30 Browning for the .303 version.

 

[ToeSmasher21]

WeeGee themselves say that it was a paper design study by a student at the School of Tank Technology. https://wiki.wargaming.net/en/Tank:GB99_Turtle_Mk1

Thanks mate, I am also trying to find evidence cause WG has been known to fabricate and lie about that stuff

 

[Scott Kenny]

Pardon me, missed this.

British Army coax guns and ammo were a mess. First you have the Vickers in .303 inch, then they chose the Besa in 7.9mm as a replacement, and finally they acquired the Browning in .30 US. Three different weapons using three non-interchangeable types of ammo. At the same time the RAF were using the Browning in .303. The RAF version is interesting because the gun design was modified so that it fired from an open bolt, thereby avoiding the the problem of cook-offs caused by overheating the breech. This would have been useful to have anyway.

Yes and no. The closed-bolt Brownings could be fitted with a synchronizer gear so they could fire through the prop. In the 1920s and 30s, even into the early 1940s, that was desired by a lot of requirements writers. (See the P-40 and early Mustangs with cowling guns on the US side, and both Bf109 and Fw190 on German side, not sure about British planes with cowl guns).

Open bolt guns are better for ground MGs, where you don't have 200-300mph wind chill and below-freezing temperatures to keep your guns cool.

With the benefit of hindsight they could have avoided all this by adopting the Browning in open-bolt form but with a much heavier barrel and a reduced rate of fire. Then when US AFVs came along, it would be a simple matter to swap out the .30 Browning for the .303 version.

No, you want/need a high rate of fire on aircraft MGs (and AAMGs), to get a large weight of shell on target in as short a time as possible. You do not need a ShKAS rate of fire on the ground, MG42 notwithstanding. There's a reason the MG1 and MG3 were slowed down to 800-900rpm instead of 1200-1500!

 

[Firefinder]

Eyeah for ground work 600 to 900 rpm is the best.

Sure 1000 plus sounds amazing.

Until you stop to think longer then 15 seconds.

Or try to carry 1000 bullets, plus 50 pounds of stuff, 10 miles by foot.

The MG42 was notorious for its hunger for bullets and was noted to be an out right PAIN to keep fed.

Which is why you dont see gatling or revolver style guns on ground vehicles outside of specialize roles that can be summed up as AA work.

 

[Scott Kenny]

Eyeah for ground work 600 to 900 rpm is the best.

Sure 1000 plus sounds amazing.

Until you stop to think longer then 15 seconds.

Or try to carry 1000 bullets, plus 50 pounds of stuff, 10 miles by foot.

The MG42 was notorious for its hunger for bullets and was noted to be an out right PAIN to keep fed.

Which is why you dont see gatling or revolver style guns on ground vehicles outside of specialize roles that can be summed up as AA work.

I was very fond of 600rpm. M60E3 goes chopchopchop...

 

[riggerrob]

Eyeah for ground work 600 to 900 rpm is the best.

Sure 1000 plus sounds amazing.

Until you stop to think longer then 15 seconds.

Or try to carry 1000 bullets, plus 50 pounds of stuff, 10 miles by foot.

The MG42 was notorious for its hunger for bullets and was noted to be an out right PAIN to keep fed.

Which is why you dont see gatling or revolver style guns on ground vehicles outside of specialize roles that can be summed up as AA work.

Eyeah for ground work 600 to 900 rpm is the best.

Sure 1000 plus sounds amazing.

Until you stop to think longer then 15 seconds.

Or try to carry 1000 bullets, plus 50 pounds of stuff, 10 miles by foot.

The MG42 was notorious for its hunger for bullets and was noted to be an out right PAIN to keep fed.

Which is why you dont see gatling or revolver style guns on ground vehicles outside of specialize roles that can be summed up as AA work.

Then why did the US Army install 7.62mm Gatling guns on some of the Humvees driven by Green Berets in Afghanistan and Iraq?

 

[Firefinder]

Then why did the US Army install 7.62mm Gatling guns on some of the Humvees driven by Green Berets in Afghanistan and Iraq?

Cause they are special forces doing SPECIALIZE raiding as such can do what ever the fuck they want and not some poor line guys who are doing 4 day foot patrols which is the actual meat and potatoes of military work.


Also needs to be mention that they used them for all of 6 weeks before pulling them for 240s cause they kept running out of freaking ammo.

 

[HoHun]

Hi,

The MG42 was notorious for its hunger for bullets and was noted to be an out right PAIN to keep fed.

I didn't check the WW2 manuals, but a 1960 Bundeswehr pocket manual describes the tactically realistic maximum effective rate of fire of the MG42 as 120 to 160 rounds per minute. The British expected 120 rounds per minute from the Bren gun:

https://www.secretprojects.co.uk/threads/5-56%C3%9745mm-nato-conversion-kit-for-mg-42-59.42012/#post-695976

You might have seen this ... German soldier operating machine gun as he's been trained to:

View: https://www.youtube.com/watch?v=B-VJERTwTJc&t=25s


Regards,

Henning (HoHun)

 

[Nik]

Comes down to logistics ?
Do you hump yet-another box of belt, or the spare barrel you'll need to fire it through ??

 

[Colonial-Marine]

I believe the concept behind the German focus on very high rates of fire for their infantry MGs was that in normal circumstances enemy infantry would only be exposed for brief periods of time. So, when you catch them in the open you want to send as much fire as possible downrange before they can move into cover. There is some logic to this, but penalties that come with that high rate of fire. In intense combat green troops must be likely to fire excessive amounts of ammunition and ruin barrels.

 

[HoHun]

Hi again,

I didn't check the WW2 manuals, but a 1960 Bundeswehr pocket manual describes the tactically realistic maximum effective rate of fire of the MG42 as 120 to 160 rounds per minute. The British expected 120 rounds per minute from the Bren gun

I just found this BAR manual that specifies that tactically, 3 to 5 round bursts are to be used (p. 186) and a total rate of fire of 120 to 150 rounds per minute (p. 161), about the same as the MG42:

https://www.ibiblio.org/hyperwar/USA/ref/FM/PDFs/FM23-15.PDF

RATE OF FIRE.-The automatic rifleman fires at the rate of fire most effective under existing conditions and generally at a rate of from 120 to 150 shots per minute automatic fire.

By comparison, the air-cooled, heavy-barrel M1919A4 machine gun is expected to fire 60 rounds per minute for up to 30 minutes:

https://www.ibiblio.org/hyperwar/USA/ref/FM/PDFs/FM23-45.pdf

2. COOLING SYSTEM. The machine gun, caliber .30 M1919A4, is provided with a heavy barrel which is exposed to the air. This factor serves to keep the gun at operating temperatures under normal conditions, i.e., at the rate of about 60 rounds per minute for about 30 minutes.

Regards,

Henning (HoHun)

 

[HoHun]

Hi Scott,

You'll note that the MG3 has a much lower rate of fire than the MG42.

It's worth noting that with the MG 3, the Bundeswehr did not acquire on of the rate-of-fire reduced variants that were available under the MG 42/59 name. Rate of fire on the MG 3 was indeed slightly reduced compared to the original MG 42, but I am not sure that was a deliberate design choice as the bolt carrier group had some improvements that apparently increased mass a little.

As the Bundeswehr certainly had institutional knowledge of the German WW2 experience, I believe that would indicate they didn't consider the high rate of fire an issue.

Regards,

Henning (HoHun)

 

[HoHun]

Hi,

I believe the concept behind the German focus on very high rates of fire for their infantry MGs was that in normal circumstances enemy infantry would only be exposed for brief periods of time. So, when you catch them in the open you want to send as much fire as possible downrange before they can move into cover.

I'd say it can be confirmed from the regulation "HDv 240 Schießvorschrift für Gewehr (Karabiner), leichtes Maschinengewehr, Pistole usw.", though this still applies to the lMG and predates the universal MG concept of the MG34/MG42.

Paragraph 256 states that the most rapid fire which still allows careful aim is to be used with all weapons, not only to hit the enemy when he's briefly out in the open, but also for the shooters not to pose a target for too long themselves.

Paragraph 260 (the first paragraph dealing with the actual firefight) states that machine gunners and riflemen can not engage in long firefights. The ideal is to strike surprisingly in a "fire raid", rapidly firing a high number of well-aimed shots in a brief period until the intended goal of the fire raid is achieved, and to go into full cover immediately afterwards (and potentially re-locate to prepared alternate firing positions).

Paragraphs 261 to 264 deal with target selection and expenditure of ammunition. It's clearly the top priority topic of marksmanship training. Paragraphs 268 and 269 are titled "fire discipline" and also address this topic.

There is some logic to this, but penalties that come with that high rate of fire. In intense combat green troops must be likely to fire excessive amounts of ammunition and ruin barrels.

I would guess that having a crew-served weapon operating under the supervision of an NCO who can be expected to explicitely order a specific target to be engaged with a definite number of rounds, this would not be terribly likely to be a widespread problem. Consider that all riflemen are trained as machine gunners, so if any gunner starts wasting ammunition, he'll probably find himself swapping roles with the assistant gunner, some other rifleman or the NCO himself within a very short time. The German infantry always drilled fire discipline into their soldiers, going back at least the Prussians with their Dreyse breech loaders, and while I'm really not an expert for infantry combat in any way, I really doubt their grunts would screw up badly enough to turn the MG42 from an asset into a liability on a regular basis. Sounds a bit like "Its bark is worse than its bite" ... ;-)

View: https://youtu.be/LcpR77N2Jn4?t=499


Regards,

Henning (HoHun)

 

[Firefinder]

I'm really not an expert for infantry combat in any way, I really doubt their grunts would screw up badly enough to turn the MG42 from an asset into a liability on a regular basis

Expect that we DO have German WW2 AARs from all the branches of that military that list complaints of the MG42 rate of fire causing logestical issues from as early as 1942 when the thing was tested.

They couldn't keep the things fed even fire discipline before the German militry everything turn to shit.

Theres a reason why 550 to 900 rpm is consider the current sweet spot for ground weapons.

fast enough to fill an area of a target with lead but still slow enough to conserve ammo.

 

[HoHun]

Hi,

Expect that we DO have German WW2 AARs from all the branches of that military that list complaints of the MG42 rate of fire causing logestical issues from as early as 1942 when the thing was tested.

As I admit that I'm quite clueless about infantry combat, I'd certainly love to learn more about these.

The effective rate of fire isn't directly tied to the cyclic rate of fire, which on the MG42 was indeed unusually high. However, just like the Allied light machine guns, the MG42 was to be fired in short bursts (different from what is shown in the American WW2 clip I linked above).

Here's a summary of the rates of fire of the MG42 compared to the Allied machine guns I found data for (and to the older German lMG):

- MG42: 120 to 160 rounds per minute
- lMG: 120 to 160 rounds per minute (in bursts of 3 to 8 rounds) - both lMG 08/15 and MG13 are illustrated in the source
- Bren gun: 120 rounds per minute
- BAR: 120 to 150 rounds per minute
- M1919A4: 60 rounds per minute (for up to 30 minutes ... slightly different role)

If there were logistical issues with the MG42, there would have been the same logistical issues with the other machine gun types, as the effective rates of fire were all very similar when they were used as intended.

So, I'm curious what the concerns of the German AARs were ...

Regards,

Henning (HoHun)

 

[mirco1961]

bar 120 rounds per minute, changing 6 magazines?

 

[HoHun]

Hi,

bar 120 rounds per minute, changing 6 magazines?

120 to 150 rounds per minute, even. That's how the BAR was to be used in combat, according to paragraph 178 in this manual:

https://www.ibiblio.org/hyperwar/USA/ref/FM/PDFs/FM23-15.PDF

A soldier was expected to take a loaded magazine out of a belt pouch and inserted it into the gun in 2 to 4 seconds, according to the manual.

One of the firing exercises in the manual gives the shooter 65 seconds to go through 6 magazines loaded with 5 rounds each, fired off in a single burst each. That's indeed 6 magazines in just over a minute, albeit with only 30 rounds fired.

Regards,

Henning (HoHun)

 

[riggerrob]

.... Consider that all riflemen are trained as machine gunners, so if any gunner starts wasting ammunition, he'll probably find himself swapping roles with ....

Regards,

Henning (HoHun)

In a perfectly-trained peace-time army yes.
But late in the war when you are reduced to a few wet-behind-the-ears conscripts, all bets are off. Who knows if they can fire their own weapon accurately, much less their buddy's weapon.

 

[HoHun]

Hi Rob,

In a perfectly-trained peace-time army yes.
But late in the war when you are reduced to a few wet-behind-the-ears conscripts, all bets are off. Who knows if they can fire their own weapon accurately, much less their buddy's weapon.

Being reduced to a few wet-behind-the-ears conscripts late in the war, the war is actually lost regardless of what machine gun these conscripts fail to employ properly ;-)

Naturally, to get the optimum from any weapon, good training is required. However, the necessity to restrict fire to short bursts and to observe firing discipline is emphasized in the BAR manual I linked just as it's in the German training manual, so I really see no reason to assume that poorly trained gunners would be any worse off with the MG42 than they would be with the BAR.

I'm actually hoping Firefinder is going to shed some light on this with some details from the German documents he mentioned, as it seems difficult to get to the bottom of this issue with fictional scenarios alone.

Regards,

Henning (HoHun)

 

[DWG]

An issue in considering the sustained rate of fire is whether or not the gun comes with a quick change barrel. The Bren and MG42 did, the BAR didn't (though the Belgian FN Mle D did). That was most important for the MG42 because it also covered the HMG role, it wasn't simply a squad MG, it had to compete with the Vickers and the M1919 in the sustained fire role. But it was also important for the Bren because the barrel needed changing after every 10 magazines, which is only 2 minutes 30 seconds at the sustained rate of 120rpm. IOW the BAR might have a sustained rate of 120 rpm, but for how long?

 

[riggerrob]

Hi Rob,



Being reduced to a few wet-behind-the-ears conscripts late in the war, the war is actually lost regardless of what machine gun these conscripts fail to employ properly ;-) ......

Regards,

Henning (HoHun)

Are you referring to the Black Watch Regiment of Canada during the spring of 1945?
They suffered 350 percent casualties between D-Day and VE Day. The supply of recruits from Canada had pretty much dried up. They were scraping the bottom of the barrel for cooks and clerks and drivers.

 

[HoHun]

Hi Rob,

Are you referring to the Black Watch Regiment of Canada during the spring of 1945?
They suffered 350 percent casualties between D-Day and VE Day. The supply of recruits from Canada had pretty much dried up. They were scraping the bottom of the barrel for cooks and clerks and drivers.

Actually, I didn't know that Canada was short on manpower, too - I was thinking of the late-war Wehrmacht, which ended up sending barely-trained, underage recruits into combat. Thanks for pointing that out, it connects to a statement by a British tank commander I recently read ... they were always short on supporting infantry. I didn't recognize the depth of the problem before!

Regards,

Henning (HoHun)

 

[HoHun]

Hi DWG,

An issue in considering the sustained rate of fire is whether or not the gun comes with a quick change barrel. The Bren and MG42 did, the BAR didn't (though the Belgian FN Mle D did). That was most important for the MG42 because it also covered the HMG role, it wasn't simply a squad MG, it had to compete with the Vickers and the M1919 in the sustained fire role. But it was also important for the Bren because the barrel needed changing after every 10 magazines, which is only 2 minutes 30 seconds at the sustained rate of 120rpm. IOW the BAR might have a sustained rate of 120 rpm, but for how long?

Good point!

For perspective, the German rates of fire are actually stated in the style of "a shooter should be able to fire X to Y rounds in 30 seconds", and with the tactical background envisioned as short "fire raids" before retreating into full cover and immediately re-deploying into a (prepared) alternate position, I think they probably weren't expected to keep firing until the barrel needed changing. I guess the idea might have been to change the barrel so when they started firing from that alternate position, they could do so with a cool barrel.

(The German term "Feuerüberfall" is sort of difficult to translate, maybe "assault by fire" would be better, but as in a military sense, an assault is associated with taking ground, I decided to call it a "fire raid". If there's a better term I'm not aware of, please let me know!)

Looking at ammunition expenditure in way, I think it's implied that a "fire raid" takes 60 to 80 rounds, regardless of the gun used, as this figure is also given by the 1937 manual written with the lMG 08/15 and MG13 in mind, which had a much lower rate of fire.

Regards,

Henning (HoHun)