The MG34 was the first German implementation of the universal machine gun concept – and really the first such fielded by any army. The idea was to have a single weapon which could be used as a light machine gun, heavy machine gun, vehicle gun, fortification gun, and antiaircraft gun. The MG34 was designed to be light enough for use as an LMG, to have a high enough rate of fire to serve as an antiaircraft gun, to be compact and flexible enough for use in vehicles and fortifications, and to be mounted on a complex and advanced tripod for use as a heavy machine gun.
Mechanically, the MG34 is a recoil operated gun using a rotating bolt for locking. It is chambered for 8mm Mauser, and feeds from 50-round belt segments with a clever and unique quick-change barrel mechanism. The early versions were fitted with adjustable rate reducers in the grips allowing firing from 400 to 900 rounds per minute, and also had an option for a top cover which would fit a 75-round double drum magazine. Both of these features were rather quickly discarded, however,r in the interest of more efficient production. However, the gun fulfilled its universal role remarkably well.
The MG34 was considered a state secret when first developed, and despite entering production in 1936 it would not be formally adopted until 1939 – by which time 50,000 or so had already been manufactured. It would comprise about 47% of the machine guns in German service when the Wehrmacht invaded Poland, but would be fully standardized by March of 1941. It was replaced by the MG42 later in the war, as that weapon was both faster and cheaper to produce and also required substantially less of the high-grade steel alloys that Germany had limited supplies of. However, it would continue to be produced through the war, particularly for vehicle mounts.
The real question is whether the standard infantry platoon’s firepower comes mainly from the machine gun or from the rifles…
“from the machine gun or from the rifles”
This depend on: which machine gun and which rifle? Germany have highly-efficient rifle-caliber machine gun, so less motivation for development of self-loading rifle than other nations.
Soviet Union has developed self-loading rifle (SVT) and put it into production, but do not manage to replace entirely older Mosin rifle. Additionally sub-machine gun (PPSh) was produced in big number, supplementing short-range fire-power (despite what some video games suggest Germans did not used MP40 on such big scale). In Soviet Union plan was to have tripod-rifle-caliber machine gun kin to light machine gun, namely DS-39 (by Degtyaryov) similar in many ways to DP (by Degtyaryov). Second worked properly, but first despite a lot of effort had little reliability, Degtyaryov did not manage to fix it, until Goryunov showed own machine gun design.
Let’s not leave America out of the mix. The Browning rifle caliber machine guns were pretty good at suppression fire and by 1943 the M1 Garand was the standard rifle for the Army and the Marines. By this point, the Browning M1918 was a squad automatic weapon (and depending on the user’s affiliation, it was either loved or hated) and other items like shotguns, SMG’s, and the M1 Carbine were left for specialized roles (to say nothing of the Johnson LMG, given to parachuting Marines). With a standardized self-loading rifle, Americans focused more on infantry marksmanship than suppressing fire. The rest is “call the artillery and reduce the other team to hamburger before advancing.” I could be wrong.
There are plenty of pictures showing beltfed air-cooled Br.1919 from battle scenes of Europe. It has usually heaps of spent casings around indicating it was not used typically as mobile implement.
Couple of things to point out, here: The German choice of concentration on the MG had an awful lot to do with the fact that they did not have the depth in trained troops that they wanted to have, and the GPMG concept was a way around that issue. The idea was to concentrate the mass of the squad and platoon’s firepower into the MG, which could be more easily supervised and managed by the few troops they had trained to proficiency. In a way, it was an answer to what they saw as a major problem–No reserves of trained manpower, due to the Versailles Treaty preventing them from having a draft in peacetime. The GPMG was supposed to obviate that need for highly-trained troops, and make the most of the ones they did have. Did it work? Well, the casualty rolls from the war show that it did, to my mind. The German Infantry punched well above its weight for most of the war, considering the limited amounts of external fire support most formations had, and the very limited motorization across the breadth of the Wehrmacht. You have to remember that the armored and modern mechanized forces were, by far, only a thin crust on an army that was dependent on rail and foot-infantry forces.
The US, on the other hand, took the route of handing every soldier a semi-auto rifle, and thinking that doing that would lead to victory. Ideally, you need highly trained and very motivated soldiers to make this work–Which we just didn’t have, because of a deliberate decision to push the highest quality recruits into the supporting branches, leaving the dregs for the Infantry formations. While that isn’t something we want to admit, or like to talk about, that is the truth–Throughout the war, the Army Infantry was a source of despair for numerous commanders and was assessed as such by most of their opponents. To make the M1 really work, the way it was envisaged, we’d have needed a much different set of troops and a different overall approach to war. As it was, we had a major mis-match between our tactics/operational intent, and the small arms we issued.
What’s interesting is how much convergence there was by the end of the war, between the German MG-centric concept, and the US individual weapon-centered approach. Where the Germans eventually issued the StG44, and moved the MG42 out of the squads, leaving them and the few proficient gunners they had time to train to be parceled out by the platoon leadership, the US put things like the M1919A6 down into the squads, acknowledging the necessity for more crew-served firepower in the squad.
Two different approaches, which wound up evolving into very similar solutions under the pressures of modern combat. It’s just too damn bad that the majority of the US practitioners who learned all this the hard way wound up demobilizing, and leaving the place-holders like Studler to determine the future of US and NATO small arms. We’ve suffered the effects of that for generations…
Doctrine decides that, and armament is generally tailored to doctrine.
The Wehrmacht doctrine, inherited from the WW1 Reichswehr, was that the machine gun was the killing weapon, and the riflemen were there to support it. This caused the Germans to develop the entire concept of the Einheitsmaschinengewehr, the GPMG concept as we know it today.
The American doctrine was that the riflemen in the infantry squad generated the “base of fire”, with the squad automatic acting as a “hammer” on points of resistance. Hence, we developed the M1 Garand self-loading rifle and the BAR.
The British doctrine was similar, thus the SMLE/Rifle No. 4 series and the Bren.
Japanese doctrine was basically the same as the Germans, thus their Hotchkiss-based HMGs and LMGs, backed up by bolt-action rifles.
If the Italians actually had a doctrine for fighting anybody more “advanced” than tribesman in colonial wars during that time period, I’ve never seen evidence of it. Other than some LRDG-type activities in the Western Desert, their tactical doctrines seemed to have stopped evolving around the year 1900, and didn’t start changing again until after they switched sides in 1943. At which point they adopted the American doctrines (witness the Beretta BM59 rifle series), except with the addition of a serious GPMG, the MG42/59.
It all goes back to an old North Africa Theater joke about “Unit ID in the desert” I learned from my uncle, Lt. Col., U.S. Army Corps of engineers, Operation Torch and Italy, etc.;
If you came upon an infantry unit “up the blue” and couldn’t ID it, the drill was to fire one shot in a safe direction.
If the response was a volley of precision, aimed rifle fire, they were British/Commonwealth.
If it was a fusillade of machine-gun fire, they were German.
If they threw grenades first and then laid on MG and rifle fire, they were Italian.
If they tried to sell you something, it was a local caravan.
And if nothing happened for five minutes and then your position was obliterated by artillery fire and/or an air strike, they were Americans.
He also said, “And if nothing happened for two minutes and you felt a tap on your shoulder, they were Gurkhas. Who would be smiling and saluting politely, and returning those big kukris to their sheaths, once they were sure you weren’t Germans or Italians.”
He nominated the Gurkhas as the scariest guys in the Western Desert.
cheers
eon
“If the Italians actually had a doctrine for fighting anybody more “advanced” than tribesman in colonial wars during that time period, I’ve never seen evidence of it.”
You are taking chances…. for “Italianbashing” 🙂
Other than that you are spot on.
“Doctrine decides that, and armament is generally tailored to doctrine.”
Well, in a sane army, that would be true. If you’re talking about the US Army, however…? It’s more a case of “design weapon, figure out how to use it, modify doctrine and tactics to suit… Ignore reality until you can’t, anymore, then do something sane…”.
Doctrine and operational intent should drive weapons design. Unfortunately, that is just something we don’t do. Note the M14/7.62mm combination, which was designed to optimally dominate the Camp Perry National Matches instead of how we were fighting our wars at the end of WWII and during Korea. Same syndrome is observable today, where the powers-that-be are looking at bringing back a full-power rifle/cartridge combination to answer the problems we have due to the self-imposed restrictions of ROE in Afghanistan.
There is a serious dearth of careful consideration and thought in the US Army, when it comes to small arms and the doctrine behind using them. You’ll look long and hard for anything at all going on like what the Germans were doing during the interwar years with their MG development and eventual doctrine. The process that created the MG34/42 family is nearly as fascinating as the guns themselves, and they are a vision into a world where the tactics and operational intent drive weapons design. A world which is, sadly, alien to the US Army.
You want another example, look at the Swiss StG-57. That’s a weapon designed to be perfectly in tune with the Swiss Army’s intent to make a fighting withdrawal into the Alps, and then attrit an invader to death with long-range fires from an individual weapon which is more a combination of an LMG with a rifle than the usual Sturmgewehr ideal of a combination submachine gun and rifle…
Also, note that when the Swiss doctrine and operational intent switched from a fighting retreat to the mountains to defending the lowlands, they changed their rifle over to something more suitable, the StG-90.
Good luck finding anything as rational and reasoned in US small arms history. We don’t do that kind of thing, at all–It’s all what’s fashionable, or high-tech for the times. Forget ever seeing a connection between doctrine and the weapons we issue… Hall carbine, anyone…?
The new rifle rounds that pretty much all of NATO wants aren’t going to be full-power. Instead, they’ll be more like some sporting rounds that were popular before WW2, that can reach out to engage point targets at 600 m or so in a rifle, or out to 800 in full-auto from the GPMG and blanket a group target, but still weigh less per round and have less recoil than the 7.62 x 51.
In fact, most of the ones they’re kicking around are in the general ballistics area of the old .257 Improved Roberts (a necked-down 7 x 57 Mauser), or the even older 6.5 x 55 Swedish Mauser.
The main thing is to come up with one cartridge for both rifle and MG that can do most of the 7.62 NATO’s job in the MG, and in the rifle can actually be effective beyond 200 m, something the 5.56 x 45mm has trouble with in any iteration.
See
Towards a “600 m” lightweight General Purpose Cartridge
,v2017
http://www.quarryhs.co.uk/Emeric2017.pdf
and
Increasing Small Arms Lethality in Afghanistan; Taking Back the Infantry Half-Kilometer
http://www.dtic.mil/docs/citations/ADA512331
cheers
eon
7.62x39mm?
“7.62x39mm?”
Not, this cartridge was designed to be effective up to 400 – 500 mm.
Additionally bullet diameter was chosen due to manufacturing reasons (smaller diameter were tested).
For cartridge of higher accuracy and Soviet origin see 6 x 49:
http://sniper-weapon.ru/boepripasy/370-patron-6kh49-mm
which fire 5 g bullet @ 1150 m/s, that give both good accuracy and acceptable recoil in full-auto weapons (in term of momentum this is 5750, for comparison 7,62×39 with ПС bullet give 7,9 g @ ~720 m/s from AKM for momentum 5688) and advantage in cartridge mass over full-power rifle cartridge (single 6×49 cartridge mass is 16,4 g that is practically equal to 7,62×39)
It has a much further range than 500mm.
Anyway, that’s what the Afghans had seems to outrange 5.56mm apparently.
“If the Italians actually had a doctrine for fighting anybody more “advanced” than tribesman in colonial wars during that time period, I’ve never seen evidence of it.”
Wait, significant Italian forces fought during Spanish Civil War:
https://en.wikipedia.org/wiki/Foreign_involvement_in_the_Spanish_Civil_War#Italy
did not they get experience from it?
Also Italians were on way of introducing self-loading rifle Fucile Armaguerra Mod. 39: https://en.wikipedia.org/wiki/Fucile_Armaguerra_Mod._39
The lack of english literature in the subject doesn’t mean there was no doctrine.
The army up till 1939 persevered into watered down 1919’s tactics (having the Arditi, which already operated as a specialty rather than an organic component, been disbanded for political reasons) in general terms, but its specialistic branches kept on innovating (ie. the Bersaglieri which operated as mechanized/fast regiments, akin to Panzergrenadiers).
“If they threw grenades first and then laid on MG and rifle fire, they were Italian.” – Brixia mortars where in fact one of the main assets of the infantry platoons, which ended up integrating 9 Breda 30s and 3 Brixia 35s. They were supposed to open fire first to soften up enemy forces, and their small projectiles were identified as hand grenades by the reciving side.
Artillery. Then tanks. Then maybe air.
“75-round double drum magazine”
Patronentrommel 34 (NOT to be confused with Gurttrommel 34) photos and description: http://www.bergflak.com/PT34.htm
Patronentrommel 34 seems to be designed for AA defense usage.
I have often wondered why there are plenty of recoil operated MGs but as far as I know no sucessful recoil operated rifles apart from the Johnson. Is there a reason I can only think maybe a succesful recoil operated weapon needs more weight/metal than would be allowed in a rifle.
Well for one thing a recoil-operated rifle is less amenable to a bayonet.
Surely thats something that can be worked around or does a bayonet need to fix to the barrel. I dont know a lot about the SMLE but doesnt the bayonet hang on a lug on the fore end and a lug on the nose cap.
“no sucessful recoil operated rifles apart from the Johnson”
Fyodorov Avtomat belong to short-recoil category: http://modernfirearms.net/assault/rus/automatic-fedorov-e.html
it was overwhelmed by circumstances, Russian Civil War preventing further production and later Red Army decision that: standardize on 7,62x54R
It was apparently also a nightmare to disassemble.
Three reasons:
1) A Machine gun profits from a detachable barrel, an a recoil operated gun with moving barrel leads to such a design
2) Reliability: A recoil operated design works better with a heavy, ideally mounted gun. If the rifle is allowed to move backwards during the shot, the gun may not cycle correctly. (This is an issue with recoil operated handguns, for example)
3)Accuracy: The barrel must return to the same point every time. In a large gun, this is easier to accommplish, and a machine gun has no issue with some spread due to the barrel not returning to battery inconsistently.
Thanks… Very well outlined.
“If the rifle is allowed to move backwards during the shot, the gun may not cycle correctly. (This is an issue with recoil operated handguns, for example)”
Most modern service automatic pistol are recoil-operated, so even if this is problem it should not be exaggerated.
“Accuracy: The barrel must return to the same point every time. In a large gun, this is easier to accommplish, and a machine gun has no issue with some spread due to the barrel not returning to battery inconsistently.”
Again this might be problem if it would to be used in sniper rifle, but otherwise? Surely it is better to have fixed barrel, but it should be noted that ever if recoil-operated arm achieve worse accuracy from vice, its accuracy might still be superior to abilities of its user when fired free-hand. Was accuracy problem in case of Johnson rifle – was there any complaints about accuracy? What about other hunting recoil-operated rifle: Remington Model 81?
Regarding Johnson self-loading rifle there was post on forgotten weapons containing pdf with Melvin Johnson’s statements about his rifles:
https://www.forgottenweapons.com/johnson-semiauto-rifle-senate-hearing/
There has to be a reason for designing recoil operated rifle – not just to be different, especially considering that gas-operated rifles for small bore ammunition are just about perfected.
Let’s say you want to design a recoil operated rifle for one single reason – to reduce felt recoil and thru it improve hit probability. Let’s say it would be justified, if you can employ sort of internal mechanism which will achieve that; e.i. to separate action from gun envelope. Now you have to give the barrel some shroud or even maybe front support, depending on design (bayonet use can be left out). Suddenly the “free floating barrel” theory which has position of untouchable relic would be thrown out of window. Or maybe new theory would be adopted? Just questions, no answers…. 🙂
“There has to be a reason for designing recoil operated rifle – not just to be different, especially considering that gas-operated rifles for small bore ammunition are just about perfected.”
There is a reason, and that reason was the Waffenamt’s prejudice against gas operation. Which was much of a piece with everyone else’s opinion, during the early days of automatic weapons. They didn’t like the fouling, which was a problem back then due to the hydrophilic corrosive compounds used in primers and powders, and they felt that the nearly-inevitable gas cutting and erosion at the port was a show-stopper. That’s one big reason gas-operated weapons didn’t get adopted by the Germans until late in WWII, and why the gas-trap guns they had were designed as such. Institutional prejudice against gas-operated weapons, essentially.
Some of which was also present in the US–Remember that the early Garand was a gas-trap design.
“Some of which was also present in the US–Remember that the early Garand was a gas-trap design.”
IIRC such design was used by Garand himself to avoid patent infringement, not effect of institutional gas-operated = bad.
Notice that U.S. forces used BAR 1918, Marlin Model 1917 (tank), Marlin Model 1918 (aviation): http://www.marlinforum.com/The-Marlin-Machine-Guns.html
I should have been more clear with how I phrased that:
It wasn’t “Gas-operated=bad…” so much as it was “Gas port drilled in barrel=bad, very bad…”. The prejudice against this was widespread and long-standing, holding back small arms design for a good deal of time.
Technically, every Heckler & Koch weapon with a roller-locked breech (inherited from the MG42) is short-recoil operated, from pistols like the old P9S on up to rifles like the G3 and even LMGs like the HK21 (there was even a .50 BMG version of that, a real monster), and they’re probably second only to the FN FAL rifle and IMI Uzi SMG in sales worldwide.
The failure of the Johnson rifle and LMG (which BTW strongly influenced the ergonomics of the German FG42) was less due to deficiency than timing. By the time they were ready for full production, the M1 Garand and BAR were already U.S. standard. And the main original customer for both, the Dutch government (who wanted them for their forces in the Dutch East Indies, now Indonesia), were under German control, followed by the Indies falling to Japan.
Those were in 7 x 57mm Mauser, BTW, so they were fairly easy to convert to .30-06, and saw limited service in the Far East and Pacific theaters with U.S. forces, notably the ParaMarines.
The two words that best describe what happened to the Johnson weapons are the ones Ian Hogg used to describe what happened to Germany’s advanced weapons projects; too late.
cheers
eon
The roller-delayed blowback in the P9S, MP5, and G3 is really quite different from the roller-locked gas-piston operation of the MG42.
I don’t see how either of them can be called a short-recoil action. The roller-locked gas-piston system, of course, uses a gas piston, not recoil; the roller-delayed blowback system, on the other hand, never locks the breech at all, and starts opening immediately.
Ben, there is no gas piston in the MG42, unless you describe the barrel/bullet combination as forming such for a very limited amount of time whilst the bullet is traveling down the barrel.
The MG42 is, just like the MG34, a purely recoil-operated weapon.
You’re right, of course. Oops.
But what gun *was* I thinking of that was roller-locked gas-piston? I guess it must have been the Gerät 06 — don’t know how I got that mixed up with the MG42.
Actually not. The strange looking muzzle serves the purpose to collect gas in a small chamber while the bullet passes through a narrow hole. The pressure acts upon the barrel to push it rearward.
eon,
Not to be pedantic, but the HK weapons are more accurately termed “roller-delayed blowback” weapons, rather than “roller-locked”. It is, I’ll grant you, a distinction of a decidedly esoteric nature, but it is there.
You’re absolutely right that the MG42 had a roller-locked breech, but the later HK systems were only roller-delayed, not locked–Which is why the chambers are fluted on those, and the MG42 doesn’t have to go to that extreme to make its system work.
Additionally, the barrel on the MG42 recoils, while the G3 and derivatives do not.
“old P9S on up to rifles like the G3 and even LMGs like the HK21”
Wait:
1) does P9S has fixed or moving barrel?
2) does G3 has fixed or moving barrel?
3) does HK21 has fixed or moving barrel?
In otherwise excellent presentation was missed one part and that is how transfer of motion from action to feed mechanism (to advance the belt) is made. Well, those who are seriously interested can find it on their own. In any, case this mechanism concentration into feed cover remained as a conceptual approach well into following western designs; it was not shared however by Russian designs, all the way to PK.
This is long time my favorite MG because of its mechanical intricacy. As much as it is slim in its profile, there is visible penalty inside in form of complexity. Recoil operated guns are generally not simple as Browning 1919 shows. In any case this was a mainstay of Wehrmacht, while considering Ian’s point on intentional visibility.
implementation of the universal machine gun concept – and really the first such fielded by any army
Madsen M1929 pre-dates MG34 by several years; and it also could be sued as LMG or MMG (tripod-mounted, with heavy barrel and extended magazines), as an AA r tank gun
“tank gun”
I never heard about tank version of Madsen machine gun. Which country used that?
[IMG]https://forum.axishistory.com/download/file.php?id=41284&sid=7b86ba7bf55a4c5af9b6f07939ae5bca[/IMG]
Madsen M29 tank version
You are quite right.
The idea of a GPMG was triggered in Germany by studying the Danish recoiling gun mount as proposed by Halvor Jessen.
The mounts weren’t just proposed, the M.1929 tripod adopted by the Danish army is functionally identical to the Lafette 34.
Both are likely based on the DRS 1927 tripod that Ian demonstrated back in 2013.
https://youtu.be/9qbbr-_QdyY?t=15m2s
I must have seen thousands of mg 34’s in films and on photos, but this is the first detailed presentation I see. Of course here on FW. I like how you move the camera more slowly than usual, so I can see the different parts in sharp detail, instead of blurred. Looking at the parts alone, you understand why they moved to the mg42. What a complex mg!
When Ian took the butt off to show how it would have been mounting inside armour, did anyone else think: “Ooo, that looks like the butt of yesterday’s Colt’s M231”?
A question to any veteran machine-gunners: Did you ever actually do a rapid barrel change in the middle of battle? I’ve always wondered if that actually took place, or only afterwards.
I have had same thought several times in past. To me changing barrel after x rounds is an ideal conception; in battle situation heat intake into barrel in likely the least of concerns.
Changing the barrel is probably trained more than it is used in combat–The number of times where you’re firing the weapon enough to require barrel changes is limited.
However, comma… You had better be trained and proficient at the task for those few times when you need to apply it, or your gun is going to go out of action very rapidly, leaving you in a Very Bad Place ™. The mark of a proficient crew that has been properly trained and which has the discipline to change out the barrels when appropriate is that their guns don’t go out of action because they’ve welded the damn barrel to the receiver, and that the barrel has gone white-hot and blown rounds out the side as it droops.
The number of times where you’re going to see this happen on the modern battlefield is limited by the availability of fire support. Before you need to fire your MG that much, you’ve generally gotten the artillery Forward Observer or the aviation FO to deal with the problem via the application of suitable high explosives. However, that does not mean that you’re not going to occasionally have the need, like at Wanat. I’ve gotten conflicting reports from that fight, about whether or not the MGs were taken out by enemy action, or because the operators were wounded and replaced by guys who weren’t properly trained to serve the guns for sustained fire.
Either way, changing the barrels out every belt or so is still a necessity, if you intend to keep firing for more than a few minutes. You can burn the barrels out in very short order, should you not pay attention to this requirement.
They trained to swap barrels every time they inserted a new belt, to the point where barrel swaps were an automatic action performed without thinking. Train as you intend to fight, and you’ll fight as you train. Source: am ex Norwegian infantry, cross-trained on the MG3. Once during an army publicity thing exhibiting guns and gear in public, an old geezer walking with teo canes scoffed at the young gunner demonstrating MG barrel swaps using an insulating cloth to grab the “hot” barrel. “That’s not how you do it!” Said the oldtimer. He dropped to prone and showed us how to use the handle end of the scraper tool to lift a barrel by its locking grooves. Dude in his nineties swapped barrels on that MG3 in two seconds flat. Turned out to be an old nazi; he’d volunteered to join one of the SS foreign regiments and was given a whole year of training on the MG-42 before being sent to the east front. Hadn’t touched an MG since 1945.
I have been waiting for this video. Great presentation. I have a question: The bolt speed is limited by having to accelerate with the barrel before unloocking. When in motion, the bolt carrier thing is seen having to accelerate at a greater rate than the bolt. Does this play a role in limiting bolt speed further?
If you look into Chinn’s book it will tell you that recoil operated guns are shooting at higher rate. In reality, barrel with still locked-in action starts to move at instant of bullet move, then is accelerated by muzzle booster. Without it the action would not have enough power to do what it does.
Now, someone may argue that bolt carrier group is accelerated thru unlocking; I do not see validity of such assertion. By mere separation it will not go any faster. In meantime pressure dropped meaning less driving force. The right way to achieve acceleration of action is thru accelerator. You see them on Browning 1919 or BMG 50cal. MG42 has this function included in barrel extension.
As I understand it:
As the bolt head rotates, it’s camming the bolt carrier/body back, so the bolt body is moving back fast, while the bolt head is moving back slow (just a little faster than barrel, thanks to helical locking lugs). As it completes its rotation (at this point the breech is fully unlocked), the bolt head abruptly speeds up and the bolt carrier slows down, so they’re both traveling the same intermediate speed — which would be substantially faster than the barrel speed.
So if I’m understanding that right, I think that momentum transfer between the fast bolt body and slow bolt head counts as an accelerator mechanism. It certainly doesn’t happen “thru unlocking”, it just happens at the same time, and because of the same rotary motion, as unlocking.
A well thought approach. Just like the delay effect of toggle mechanism. This means, every rotating bolt through camming also having a delay effect through momentum transfer.
Simply, bolt head is forced to rotate through camming by bolt carrier as fighting against to friction supported by remaining gas within the barrel, therefore, the rotating speed should be slower than the accererelating thought camming effect creates. This means, no significant action of speed difference occurs. However, M16 action should be an exception since the pressure in the barrel nearly is equal with the opposite side, within the inline gas piston.
We are working based on assumptions, Ben. To evaluate the situation properly we would have to see velocity profiles of individual parts in time or specific portions of their travels. Let’s not forget, barrel does not have constant speed thru its entire travel (although you might think this is irrelevant because it is short, true). Also, there is addition of barrel return spring effect (one of inconveniences of recoil operated system), friction being ommited. It is little too complex affair to describe it in few sentences.
However, your point of considering momentary bolt body/ carrier speed increase is valid (again, loses by friction being omitted), at least for short period of its travel. My basic classification of recoil operated system is based on fact whether there is a purposeful part (this being an accelerator) included or not. Browning machine-guns as one example are known for having them.
“If you look into Chinn’s book it will tell you that recoil operated guns are shooting at higher rate.”
I would say that linking principle used (as whole) to Rate-Of-Fire give little sense. Every design has its own rate-of-fire (known as cyclic) and probably minimal and maximal which can be achieved without core rework and without losing too much reliability. Example against above statement is Chauchat machine gun with its moderate 250 rpm.
Additionally both types can be made with choice of Rate-of-Fire feature.
Daweo, you as a man of knowledge know that there are exceptions to every ‘rule’ in firearms. I was first thinking to offer an exception myself – this being 7.62mm Shkas MG; high rate of fire but gas operated. I thought you will come up with that one and you would be right.
Still, if you look at any introductory course on operating systems you hit on “recoil operating systems have high rate of fire” assertion. How it was created? Probably by time by examples of specific designs. It became a mindset whilst it can be argued against on case to case bases.
This observation might be effect of analysis of rifle-caliber aircraft machine gun as used during World War II, where high rate-of-fire is desirable. Chinn, if I am not mistaken, worked in United States, thus he probably have access:
-data for, if not example of, Browning .303 Mk II aviation, firing 1150 rpm (as Great Britain was ally)
-intelligence data for MG 81, as used by enemy forces, firing 1500-1600 rpm
Other example of fast firing gas-operated aviation machine gun is French DARNE, which might be overlooked due to fast Fall of France.
The Stg-45 (M) system, developed by CETME, was very different from that uses by MG-42 tough both use rollers. The MG has a recoiling barrel and Stg-45/CETME has a fixed one. So the MG was recoil operated as it has a locked breech at the moment of firing whereas Stg-45/CETME was delayed blowback, in which bolt was not firmly locked at the moment of firing(Spanish CETME described it as semi-rigid).
Putting the development of the GPMG into context will be difficult. First, Germany was trying to produce one machine gun that could do everything–light machine gun (squad automatic weapon), heavy machine gun (sustained fire battalion machine gun), tank gun (coax, pintle mount, socket mount on hull), aircraft gun (flexible and fixed and turret gun), anti-aircraft gun, fortress gun, and navies have requirements for close-in defense of ships and smaller boats. The MG-34 was a jack of all trades.
There’s a problem with belt-fed light machine guns at squad level–the squad must become a light machine gun squad. The BREN Gun used magazines–as did the Japanese Type 96 and Type 99. A belt-fed machine gun really needs a crew of five or six to keep it humming. A light machine gun (magazine fed) does well with a crew of two. The automatic rifle is an individual weapon–despite US Army attempts to turn it into a crew-served weapon (WW2 Army BAR teams were three men!). The GPMG is heavier than the LMG and adding spare barrels, tripod, and enough ammo to exploit its capabilities gobble up squad resources. Had the Germans fielded the MG-34 in the year 1918 they wouldn’t have deployed this gun down to the little three and four man storm groups because there’s no room for the weapon, no way to meet its requirements. As a replacement for the MG08/15 light machine gun in a machine gun SQUAD the MG-34 would have been grand. Even when fielded in a French-style 1918 rifle squad instead of the Chauchat the MG-34 was workable. Germany in 1939 used a four man squad machine gun element along with a squad leader, an assistant squad leader, and a seven-man rifle element–but by the Battle of France this had been trimmed to a less-clumsy eleven-man squad with a three-man machine gun team. British Army rifle squads had a two-man BREN Gun team.
Post-war experience led Britain to keep around BREN Guns in 7.62mm NATO to replace some of their MAG-58 squad-level machine guns for foot-mobile operations–the MAG-58 was not used to its full potential with just two guys. The USSR eventually developed the RPK Squad Automatic Weapon edition of their famed AK series–for when their excellent belt-fed PK was just too much burden on the squad and replacing the RPD belt-fed light machine gun. Note that there was a light support weapon edition of the AK-74 as well. The M249 Squad Automatic Weapon was fitted to feed from belts or from STANAG 5.56mm rifle magazines and became the focus of fire teams in Army and Marine Corps rifle companies–the Marines adopted the M27 IAR because “mobility” means using small teams instead of big platoons and using dispersed operations. The MG-34 and MG-42 “universal machine gun” worked as a squad level weapon even when some German formations issued two machine guns per “rifle squad” in the Panzergrenadier units. The vz26 was prized for foot-mobile units and in city fighting, but was rare–the MG-34 and MG-42 were the standard.
The shortcomings of the MG-34 as a squad level weapon, the shortcomings of the Kar98k and MP-38 as individual weapons and the failures of the various German semi-automatic rifles in full-bore 7.92x57mm led to the adoption of the assault rifle–German industry was too disorganized to make more than token fielding of the assault rifle possible. Note that the StG44 was supposed to replace all squad-level weapons (rifle, submachine gun and GPMG) in a smaller, more-mobile 8-man German squad (by this time the official rifle squad strength was down to 9 men) and there were experiments with six-man squads; this was bringing back the lessons of Great War trench combat on the Western Front, that elements smaller than the squad were more mobile, more stealthy, more survivable and could infiltrate enemy territory more easily. In the smaller squads there just wasn’t the manpower to operate a GPMG to its potential–and the assault rifle in these smaller formations was just as effective in offensive operations as the more-expensive GPMG.
GPMGs got abused quite a bit when used by special forces. Imagine using the MG-34 in room-to-room combat as if it were an Uzi submachine gun–the Israelis did that with their MAG-58 (and more power to ’em!). Some special forces formations of the 2oth Century carried a GPMG in four or five man teams when expecting offensive operations–and experience created chopped down GPMGs and eventually SAW versions of weapons such as the M60. The trouble with these specialized GPMGs was that bureaucratic mindset is “machine guns are machine guns” and their 19th Century thinking is that all machine guns are artillery pieces. That mindset isn’t any worse than criticizing Custer for leaving his Gatling guns behind before getting his command killed at the Battle of the Little Big Horn (Custer also left behind his three-inch field guns, his command’s sabers, and about 25% of his personnel!) because the armchair commando can’t tell the difference between a Gatling Gun and the AK-47!
World-wide the GPMG became the standard squad automatic weapon despite some flaws. For pure infantry action, for work in built-up areas or close terrain (jungles and such) the LMG (such as the BREN Gun) was superior, and the problems of a 7.62mm machine gun in a squad of riflemen armed with the 5.56mm assault rifle eventually led to the 5.56mm SAW and Light Support Weapon–and the USMC’s Infantry Automatic Rifle.
Despite the MG-34’s reputation, the Luftwaffe wanted an individual weapon for the squad role and developed its FG-42 because close combat wasn’t the forte of the MG-34. I called the MG-34 a jack of all trades–the FG-42 was another attempt to produce one weapon for all uses. The MG-34 concept eventually became the world standard and the FG-42 went away–unless you count the FAL and G-3 rifles.
I wonder if the US Army deliberately botched its attempt to reverse-engineer the MG-42 during World War Two? By 1957 the US Army adopted its first GPMG to replace the M1917A1, the M1919A4 and the M1919A6–the flawed M60 general purpose machine gun. The M60’s major flaw was the same flaw shared by all GPMGs–it wasn’t really as efficient as a squad-level weapon as purpose-built light machine guns and at the fire team level there just isn’t the warm bodies to run the gun to its potential–might as well have all assault rifle, or a mix of automatic rifles (such as the BAR) and submachine guns. The GPMG concept worked because the squad machine gun could be configured as a heavy machine gun for the defense, and even the “heavy machine gun sections” could function in the offensive as additional light machine gun teams attached to assault platoons.