Jump to content

Tank-Borne Machine Guns (Hull Mounted and Otherwise)


Poopstain

Recommended Posts

Hello Gentlemen:

     As you all know, the machine gun was very prominent on the first tanks--even to the point of comprising the entirety of the armament in many cases.  And this makes sense, considering the situation pertaining when the very first tanks appeared--the main need was to find a way to clear wire and trenches, if you will--and tank v. tank combat had not even been thought of yet.  

     Now jumping ahead a bit, at a certain point it seems nearly all tanks included at least a turret mounted (usually co-ax) and a hull machine gun.  While the interwar period gave rise to an awareness of the likelihood of some tank v. tank combat, apparently the belief that the tank would often be "assaulting infantry" meant that the hull machine gun was still seen as valuable if not integral to the tank's main role.   I am assuming (quite possibly wrongly as I am a crunchie -- hat tip Bojan--so please advise) that as far as "close in defense" was concerned, a co-ax machine gun would have been the preferred tool--seems to me that a hull machine gun makes sense mostly in the context of "assaulting" infantry (feel free to correct me).  

     Yet by the second half of WWII, hull mounted machine guns seemed to be on the verge of becoming extinct--as I understand it primarily because of concern that the "hole" necessary for mounting the gun weakened the glacis plate, but I must also presume because it was believed that the hull machine gun was really not all that useful/necessary any longer.   As a crunchie, my guesses as to the rationale behind this are as follows:

     1.  Tank v. tank combat had come to be a much more important consideration in tank design.   Yes yes I know that the almighty Sherman mostly used its miraculous 75mm peashooter against non-AFV targets, yet still at some point during actual combat  it had become clear that you really couldn't start worrying too much about the axeman who might kill you from five feet away until you had dealt with the bowman who could smite you from 100 yards.   In other words, protection vs. the hornet had begun to trump swatting the fly.  

    1(a) Ranges were increasing.   

     2.  Germany (which kind of set the fashion for the most part) was now primarily on the defensive, so machine guns now became much more a matter of defending tanks against suicidal infantry than mowing down lines of infantry cowering in trenches or improvised fortifications.  

    QUESTIONS BEING:  

     Why did multiple machine guns in general--and the hull machine gun in particular--go out of fashion?

     What are your thoughts about machine gun mounting on tanks generally---now and then?

     For any actual tankies out there---how did you view the machine gun?   Did you actually think of it as something you might likely end up using against

         Infantry?   Did you?   What do you think has changed in this regard say from 1916 to the present?

     Thanks in advance and sorry for the length and open-ended nature.

 

Le Stain du Poop

   

Link to comment
Share on other sites

  • Replies 166
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Ref WWII, it's worth noting that both the Germans (with the Stug) and Americans (with tank destroyers used for infantry support) felt the lack of a co-ax was a serious issue based off their combat experience.

The Americans were stuck; the TD designs were pretty much locked in, though crews field modified their turret top MG mounts, which were originally optimized for AA work, to be less vulnerable vs. infantry.  The Germans, having run into the issue earlier, worked both with adding bow machine guns and by '44 were going the RWS route, with the Rundumfeuer-Maschinengewehr .   This had advantages (vs. a bow gun) of 360 degree fire, which was a particularly big issue for the Stug, not putting an extra hole in the glacis, and eliminating the vulnerability of the loader using the external MG.  The external MG, even with the gun shield, was vulnerable from the side and presumably was vulnerable to 14.5mm fire going right through the shield.

Good image of the Rundumfeuer-Maschinengewehr operation here (can't imbed the photo because it's not at an https location)

 

Edited by CaptLuke
Link to comment
Share on other sites

4 hours ago, CaptLuke said:

Ref WWII, it's worth noting that both the Germans (with the Stug) and Americans (with tank destroyers used for infantry support) felt the lack of a co-ax was a serious issue based off their combat experience.

The Americans were stuck; the TD designs were pretty much locked in, though crews field modified their turret top MG mounts, which were originally optimized for AA work, to be less vulnerable vs. infantry.  The Germans, having run into the issue earlier, worked both with adding bow machine guns and by '44 were going the RWS route, with the Rundumfeuer-Maschinengewehr .   This had advantages (vs. a bow gun) of 360 degree fire, which was a particularly big issue for the Stug, not putting an extra hole in the glacis, and eliminating the vulnerability of the loader using the external MG.  The external MG, even with the gun shield, was vulnerable from the side and presumably was vulnerable to 14.5mm fire going right through the shield.

Good image of the Rundumfeuer-Maschinengewehr operation here (can't imbed the photo because it's not at an https location)

 

Thanks for the response Luke and nice photo.

 

Anyone else?  

Link to comment
Share on other sites

On 2/18/2022 at 7:10 PM, Poopstain said:

Why did multiple machine guns in general--and the hull machine gun in particular--go out of fashion?

Typically, the operator of the hull-mounted MG was the radio man, to give him something to do while he wasn't doing his radio thing. As radios became easier to operate and no longer required a dedicated specialist to do the job, the logical step twas to eliminate the position; giving an MG to drivers is usually not a good idea because driving already is a full-time job, especially in combat situations. As internal space in any combat vehicle comes at a high premium, you'd rather repurpose the two cubic meters for something else (e.g. fuel, main gun ammunition stowage), especially if the elimination of the gun port makes your tank less vulnerable at the same time.

Link to comment
Share on other sites

7 minutes ago, Ssnake said:

Typically, the operator of the hull-mounted MG was the radio man, to give him something to do while he wasn't doing his radio thing. As radios became easier to operate and no longer required a dedicated specialist to do the job, the logical step twas to eliminate the position; giving an MG to drivers is usually not a good idea because driving already is a full-time job, especially in combat situations. As internal space in any combat vehicle comes at a high premium, you'd rather repurpose the two cubic meters for something else (e.g. fuel, main gun ammunition stowage), especially if the elimination of the gun port makes your tank less vulnerable at the same time.

Very interesting Snake--never thought of that......

Link to comment
Share on other sites

On 2/18/2022 at 7:10 PM, Poopstain said:

What are your thoughts about machine gun mounting on tanks generally---now and then?

They are quite useful for anything that can be killed with a coax and doesn't require a main gun round. Also, indispensable for suppression while you maneuver to another location. But you want it stabilized and integrated into the fire control system. I have witnessed a number of shootings on the range with a Marder / Leopard team that failed because the Leopards took out most of the infantry targets (the pass/fail rating expected a roughly even distribution) simply because stabilized gun plus laser range finder plus thermals allowed for engaging so many targets in such a short time that often the man plates were down before the IFV was done with their ranging shots.

I'm more critical about commanders' MGs. Americans love them, the Russians seemingly too, so maybe they are on to something. At the same time I think that commander of a combat vehicle is also a full-time job and the shooting is best left to a gunner. And then the question is, what targets do you have that require the cal .50 because 7.62 isn't good enough but which does not yet warrant a main gun round. Not saying that it's impossible to find examples, I'm just not convinced that the obstruction of view for the commander and the additional danger of getting fixated on a target during gunnery is a net-positive tradeoff.

Link to comment
Share on other sites

3 minutes ago, Ssnake said:

They are quite useful for anything that can be killed with a coax and doesn't require a main gun round. Also, indispensable for suppression while you maneuver to another location. But you want it stabilized and integrated into the fire control system. I have witnessed a number of shootings on the range with a Marder / Leopard team that failed because the Leopards took out most of the infantry targets (the pass/fail rating expected a roughly even distribution) simply because stabilized gun plus laser range finder plus thermals allowed for engaging so many targets in such a short time that often the man plates were down before the IFV was done with their ranging shots.

I'm more critical about commanders' MGs. Americans love them, the Russians seemingly too, so maybe they are on to something. At the same time I think that commander of a combat vehicle is also a full-time job and the shooting is best left to a gunner. And then the question is, what targets do you have that require the cal .50 because 7.62 isn't good enough but which does not yet warrant a main gun round. Not saying that it's impossible to find examples, I'm just not convinced that the obstruction of view for the commander and the additional danger of getting fixated on a target during gunnery is a net-positive tradeoff.

I always wondered how often that turret-top "AA" heavy got fired.   Seems more like a placebo than anything.....

Link to comment
Share on other sites

The Danish Army did away with them a few years ago, and rather placed two flat storage boxes for carbines between the hatches. If you're buttoned up because of all the surrounding air's high metallicity, telling the loader to not be a pussy and stick his head out to man the MG is not the ideal move for morale. And if you can stick your head out because the overall threat level is tolerable, and if you need to cover the high arcs while you're passing through a built-up area, two assault rifles do a better job than a single AA MG. No belted ammo supply, but faster reaction times. I think that decision made a lot of sense.

Link to comment
Share on other sites

I have always found Leclerc setup interesting - coax 12.7 where it benefits from stab/FCS, and additional remotely operated 7.62 for secondary threats and all-around close  protection. Yes, 12.7 has less ammo than 7.62 coax, but overall Leclerc has 3000 x 7.62 and 1100 x 12.7, which is close in the number of rounds (and probably better in overall efectiveness) to 4750 in Leo 2, and way better than 2000 x 7.62 + 300 x 12.7 on Soviet/Russian tanks.

Link to comment
Share on other sites

They have decided to downsize to 12.7 on Leclerc since 20mm has became iffy for fighting vs IFVs, loosing it's appeal as a secondary weapon.

I have to look at local "destruction norms" ('ie. how many rounds of what caliber you need vs typical soft targets like truck, sandbagged emplacement etc) for exact details, but I am pretty sure 12.7 needs about 3 times less than 7.62, difference being even larger with specialized rounds (AP/API/HEI etc). So for all purposes, for destruction fires 1100 x 12.7 is equal to at least 3300 x 7.62. Ofc, for suppression it does not really matter which caliber it is, so 12.7 clearly loses there, but there is an additional 7.62mm for that purpose.

IMO, RWS 7.62mm that can be slewed to a main FCS and operated by gunner if needed would be pretty good solution in addition to 12.7mm coax and would not burden a TC. It should be also mounted on turret where it obstructs TCs view the least. TC and loader (if present) should use carbines for a local security.

Link to comment
Share on other sites

I fired a lot more with Coax in Iraq than I did main gun.

It is worth observing that when developing Pershing, Ordnance was inclined to ditch the bow gun in favour of additional stowage for main gun. This was specifically rejected by ETO who insisted upon both retention of the hull gun and stowage of 70+ main gun rounds, which resulted in Pershing having to be significantly reconfigured inside, at the cost of some usability.

If a German with a Panzerfaust showed up within line of sight of the bow gun, there was nothing else which could react as quickly whilst under armored protection, and you didn't have enough time to swing a coaxial onto the target. Further, the bow gun was semi-stabilised by use of the bow gunner being able to do a little off-the-shoulder compensation. Although Armored Force recommended the use of the stabilised coax for speculative fire while on the move, units which didn't know how to use the stabiliser were reduced to merely using the hull gun.

Link to comment
Share on other sites

2 hours ago, Manic Moran said:

I fired a lot more with Coax in Iraq than I did main gun.

It is worth observing that when developing Pershing, Ordnance was inclined to ditch the bow gun in favour of additional stowage for main gun. This was specifically rejected by ETO who insisted upon both retention of the hull gun and stowage of 70+ main gun rounds, which resulted in Pershing having to be significantly reconfigured inside, at the cost of some usability.

If a German with a Panzerfaust showed up within line of sight of the bow gun, there was nothing else which could react as quickly whilst under armored protection, and you didn't have enough time to swing a coaxial onto the target. Further, the bow gun was semi-stabilised by use of the bow gunner being able to do a little off-the-shoulder compensation. Although Armored Force recommended the use of the stabilised coax for speculative fire while on the move, units which didn't know how to use the stabiliser were reduced to merely using the hull gun.

Very interesting MM thanks for that.     May I ask* about the circumstances of your coax firings?   Were you actually aiming at individual "soft" targets, or more just trying to keep any potential heads down, or???

*I guess I just did eh?

Edited by Poopstain
To edit.
Link to comment
Share on other sites

7 hours ago, bojan said:

They have decided to downsize to 12.7 on Leclerc since 20mm has became iffy for fighting vs IFVs, loosing it's appeal as a secondary weapon.

I've never found anything that detailed what the rationale was, but this explanation is a bit unsatisfying. Assuming that a 20mm and a 12.7mm can be accommodated without critical penalties, the 20mm would be more effective against all types of targets, including infantry in the open, on account of producing fragments whereas a 12.7mm still needs a direct hit. If the ammo load of the 20mm could omit AP entirely, on account of 20mm AP not being good enough for light targets anymore - even better. 

The problem in the leclerc is that there isn't any space for a 20mm and there could not be any without a significant enlargement of the turret. Even the existing 12.7mm is installed in a rather awkward way, making it impossible to reload the 200-round ready box even when combat is imminent. @Manic Moran might have a few words about that, I think. So I'd suspect that 12.7 was just the biggest they could get away with, not that it was a favourable option.

7 hours ago, bojan said:

I have to look at local "destruction norms" ('ie. how many rounds of what caliber you need vs typical soft targets like truck, sandbagged emplacement etc) for exact details, but I am pretty sure 12.7 needs about 3 times less than 7.62, difference being even larger with specialized rounds (AP/API/HEI etc). So for all purposes, for destruction fires 1100 x 12.7 is equal to at least 3300 x 7.62. Ofc, for suppression it does not really matter which caliber it is, so 12.7 clearly loses there, but there is an additional 7.62mm for that purpose.

In terms of suppressive effect, there were actually a couple of studies on how effectively various weapons can compel soldiers to stay in cover, and 12.7 was at least not inferior to 7.62 if not better, though I can't find the references to share right now. 

Link to comment
Share on other sites

Benefits of 12.7mm for suppression is purely psychological, but than again so is an idea of suppression. :) But as such it is hard to accurately measure, unlike how many rounds takes to destroy average truck. On the plus side for 12.7mm can be used at way longer ranges, so it enables suppression at distances where 7.62mm will be less adequate.

Link to comment
Share on other sites

Quote

I've never found anything that detailed what the rationale was, but this explanation is a bit unsatisfying. Assuming that a 20mm and a 12.7mm can be accommodated without critical penalties, the 20mm would be more effective against all types of targets, including infantry in the open, on account of producing fragments whereas a 12.7mm still needs a direct hit. If the ammo load of the 20mm could omit AP entirely, on account of 20mm AP not being good enough for light targets anymore - even better. 

Turret space was actually an issue. From a Leclerc commander:

4) AMX 30 had a 20 mm coaxial gun, while Leclerc moved back to a more standard 12,7 mm M2 machine gun. Did you consider it to be a good decision?

You cannot imagine how the French tankers loved the 20mm. But this gun was just too big to fit in the Leclerc turret. The choice of the 12.7 is not, for me, the best one. The 12.7 is still a big MG and the space in the turret is limited. That s why we have only 150 rounds ready to fire. It s a kind of nightmare to refill the ammunition box. It could have been a better choice to have a 7.62 coax with 2500 rounds.

http://alejandro-8en.blogspot.com/2021/01/interview-with-former-leclerc-crew.html

The installation of the 20mm gun in the AMX30 was not without it's perks. It was a tight fit and tricky to use. This is probably why Spanish Army decided to install a classical 12.7mm instead.

From the same Leclerc commander, when he was in an AMX30. He would be very careful about letting gunner handling it.

The 20mm gun was a dream. Powerful, accurate, reliable it could replace the main gun in many different situations.

This gun was pretty big to fit in the turret but it worth it. It was designed as an anti-vehicle, anti-personal and anti-aircraft gun. The good thing with this gun is that we can choose what kind of shells we put in the belt. The typical belt was 3 armour-piercing shells and 2 explosive shells.

The average range was 1200-1300 meters in destruction mode and 1900-2000 in “suppression” mode.

This gun was a pretty hard to use and requested a high trained loader. I used it both with national service loader and professional loader. On the firing range, it was a good sigh of professionalism when your 20mm worked properly. It showed that as a tank commander, you well trained your crew and your loader in particular.

This gun was also good because of the number of ready-to-shot shells. The maximum length of the belt was almost 200 shells without reloading the gun. It was comfortable enough for the crew lol.

http://alejandro-8en.blogspot.com/2021/04/interview-with-former-amx30-commander.html

Link to comment
Share on other sites

On 2/21/2022 at 5:05 PM, Ssnake said:

Typically, the operator of the hull-mounted MG was the radio man, to give him something to do while he wasn't doing his radio thing. As radios became easier to operate and no longer required a dedicated specialist to do the job, the logical step twas to eliminate the position; giving an MG to drivers is usually not a good idea because driving already is a full-time job, especially in combat situations. As internal space in any combat vehicle comes at a high premium, you'd rather repurpose the two cubic meters for something else (e.g. fuel, main gun ammunition stowage), especially if the elimination of the gun port makes your tank less vulnerable at the same time.

Where as with British tanks the hull MG operator was actually just a co-driver, someone to swap places with the driver and generally a 5th crewman for other tasks. The British practice was to put the wireless set in the turret and have the loader operating as the alternate wireless operator (or the commander if there is no loader). The flick functionality of the WS 19 allowed rapid changing between 2 frequencies on the A-SET and the B-set was selected (from the A or the Intercom) by use of the control box(es) that the Commander, Gunner and Loader could use. 

Some vehicles might have had some alternate controls to allow the hull gunner to assist in driving even if it was just steering and throttle control. Full duplication of controls wasn't a thing. Usually it meant short halts to check fluids and move crew around to spell folks for long road marches. 

But as Snake notes, the hull was vital storage space as ammo for the main gun became larger. This more or less culminated with the Firefly. You can see how the follow on Centurion Cruiser Tank dispensed with the hull gunner entirely. Though you can see with the Churchill BlackPrince, also armed with the 17 pounder was able to retain the hull gunner. I suspect some of that is because as tanks go, the Churchill has a LOT more space in the hull sponsons than most tanks did. The sheer amount of belted ammo they could stuff into the sponsons (12 boxes at 225 rounds each to the rear per side) along with a space for personal kit and a generator set behind the driver and other gear demonstrates that. 

Left sponson from the driver's position looking towards the hull gunner's position. 

http://www.armourinfocus.co.uk/a22/stowage/ch1stow3.png

Edited by rmgill
Link to comment
Share on other sites

OH, vis a vis accuracy. Fletcher notes that crews comparing the US M1919 in Shermans vs The Hull mounted BESA MG on Churchill and the like saw differences. The M1919 was a spray down that hedgerow sort of weapon. Since you had to walk the gun onto target by firing through a periscope it was more or less mandatory. On the Churchill and other BESA armed Coax Tanks, you had an aiming telescope that allowed you to shoot from where you saw the muzzle flashes. 

You can see the top cover has a retained cross pin that engages a portion of the rear of the  BESA receiver. The grip is also the charging handle. To withdraw the bolt, you depress a lever on the left side of the grip to disengage it from the receiver and then move the whole assembly forwards and then pull it back with the bolt held by the sear. The barrel reciprocates and moves backwards a short distance and then unlocks from the bolt, but it is a gas operated system. I guess I need to take some detail photos of my own BESA parts kits to show these bits off. 

 

Edited by rmgill
Link to comment
Share on other sites

Centurion prototype had a 20mm co-ax, but that was not retained.  Some later Centurions of course had the .50cal ranging machine gun as well as a .30cal.  There were occasions in VN where the .50cal and the .30 were both used as co-ax, but as ranges were short, and armoured opposition that needed to be ranged not really expected, the use of the ranging .50 in that role was acceptable. 

Link to comment
Share on other sites

7 minutes ago, DougRichards said:

Centurion prototype had a 20mm co-ax, but that was not retained.  

Wasn't there ALSO a 7.92mm coax? The polsten cannon was I think able to be aimed independently of the main gun as well. 

There was also a hull roof mounted BESA turret prototype but that was not retained as the extra crewman took up room that was more needed for main gun ammo. 

Link to comment
Share on other sites

Yes there was MG co-ax in some prototypes, others has a rear facing BESA in the turret rear.  The British, as they had some time at this point, probably gave a good deal of thought and analysis of the best combination of weaponry to be carried.

Link to comment
Share on other sites

11 hours ago, Manic Moran said:

It is worth observing that when developing Pershing, Ordnance was inclined to ditch the bow gun in favour of additional stowage for main gun. This was specifically rejected by ETO who insisted upon both retention of the hull gun and stowage of 70+ main gun rounds, which resulted in Pershing having to be significantly reconfigured inside, at the cost of some usability.

The sentiment desiring retention of the bow gun was echoed by the 442 tankers (344 enlisted men and 98 officers--75% of which were company grade--representing 12 armored divisions and 10 separate tank battalions, with combat experience ranging from 2 days to 30 months) interviewed by the General Board, USFET, in its Study Number 53 Tank Gunnery:

Quote

b. All interviewees desired a caliber .30 bow gun. Wider traverse, increased depression, and incorporation of a sight were universally requested. On 26 September 1944, Twelfth United States Army Group requested development of a sight with at least two power magnification. The European Theater of Operations concurred. The Army Ground Forces Equipment Review Board recommended that "an infinity sight and linkage" be provided.

c. The bow machine gun mount weakens the front plate. Consequently the Germans often aimed at the bow gun. Mounting the gun in a blister on the side of the tank will overcome this problem. However, the interviews revealed that the bow gun(s) must be able to cover the ground immediately in front of the tank and between the tracks, irrespective of the field of fire of the coaxial gun.

d. The General Board, United States Forces, European Theater recommends that:

     (1) All tanks be equipped with a caliber .30 bow machine gun, equipped with sight, and having greater depression and traverse than at present.

     (2) Relocation of the bow gun in all tanks be investigated. Bow gun(s) must be able to cover the ground immediately in front of the tank and between the tracks.

     (3) Consideration be given to providing magnification in sights for bow machine guns.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...