Alternative light and anti-tank guns, 1935-45

[tomo pauk]

People were talking about the AT guns of pre-war and wartime, so why not give it a dedicated what-if thread

IN 1935-36-37 the Germans could have made better choices, one of them should have been build 47-50mm AT guns instead of 37mm so the Divisional artillery had to save the day so many times when the 37mm's didn't work.

I don't know. Pre war the 37mm/2pdr seems to have been perfectly adequate for AT use. The 5cm PAK was more than twice as heavy as the 37mm one. Of course pretty soon tanks had enough armor that the 5cm PAK wasn't enough either.

Note that thread is about all the ww2 belligerents, including the countries that will just be buying the guns for their armed forces.
Not about the tank guns, since these have their additional set of requirements.

 

[Shortround6]

A lot of times Armies built anti-tank guns based on their own tanks, not what their enemies were building for tanks. Germans were rather famous for this in 1930s and 1940.

The German 37mm Pak 36 was the poster child for this. It was designed in 1924-28 (in secret) for man/horse transport and it was a very good gun for it's day. French and others were using old French 37mm trench guns.

Germans kept their new gun and built a new carriage for motor transport by 1934 and sent it to Spain in 1936. It gathered a fair reputation and was sold/licensed/copied by a number of countries. Trouble was that the French didn't stick the script for tank development and started build hundreds and then thousands of small tanks with enough armor to give the German gun trouble.
While the French had several thousand of the old Renault 1917/18s in 1935/36 they started building the new tanks.

as a tank overall it was pretty bad........but..............it had enough armor to give the Pak 36 trouble. Maybe the Pak 36 could take it out with one hit, or it may take 6 or more. Depends on range, angle, luck and the phase of the moon. Trouble for the Germans is that the French were building this Renault, a similar Hotchkiss, and welded FMC. And they were working on a larger medium tank and a heavy tank.
The Germans were working on a new gun, the Pak 38, but in the interests mass production, common training, ammo standardization with the tank units ( a real joke considering how things ended up) they stuck with Pak 36. They put the Pak 38 plans/drawings in few drawers incase it might be needed at a future date and cranked out Pak 36s like the famous hot rolls. Which worked in Poland. AND then did NOT work in France against tanks they knew had existed for several years and did not work against the newer (but rare) British tanks.
Much of the German army rolled into Russia with the Pak 36 and while it may not have been quite as predictable without hindsight the results for the Germans were pretty horrible.
German allies using the Pak 36 in 1942 got hammered.
Americans had 'copied' the Pak 36 to a large extent, made the barrel longer and a bigger cartridge case but not enough to really put it in a different class and went to war in 1942 with a 37mm gun as their standard AT gun. Fortunately for the Americans they had another 9-10 months before getting into combat with the Germans and by that time they were reequipping with the 57mm At gun (courtesy of the British) so the dependence on the 37mm didn't last long.
Russians had purchased/licensed the German 37mm gun and then designed a 45mm barrel for it and plunked the bigger barrel on the same carriage. It was not a Pak 38 but it penetrate at around 900 meters what the 37mm could do at 400 meters. Considering the "standard" German armor of 30mm (a bit heavier in the front) this was pretty good even if not outstanding.
We are getting into the grey area dividing light/handy weapons which can be moved about by hand by 2-6 men and weapons that motor vehicles/ horses to go any distance and the really big guns where you need 4-8 men just to hook in on a truck/tractor. Moving more than a dozen meters is impossible.
This is generally the 50mm to 57mm gun area. The 75mm-76mm and up need motor traction of some sort.
The 45-47s can fall into the smaller catagory or fall in with the 50-57mm guns. Soviets had a really high velocity 57mm but it was on 76mm field gun carriage. The 57mms were pretty much the upper limit on moving by hand.

British had the plans for their 57mm drawn up in 1938/39 and again, left them in the draw until they thought they needed them.

 

[Frog]

In 1940, the basic tracked infantry French AT guns were the semi auto 25 mm SA-L 34 gun (some were also used by the British). As they were not enough, they were completed in the infantry by the WW I era 37 Model 1916 TR gun.

The Model 1937 47 mm gun, adapted from a Navy gun, was used by the artillery AT units in 12 guns divisional batteries. The luckiest were half track drawn (Kégresse P 17 E), the others horse drawn. About 70 were also mounted on Laffly W15 6x6 trucks as mobile AT assets with good results. This was one of the inspirations of the US Tank Destroyers doctrine.

 

[tomo pauk]

Looking back from almost a century worth of time, it seems to me that many times the militaries were trying to reinvent the wheel.

Germans - there was the 5cm gun & ammo capable for 650 m/s with the almost 4 lb shell, as well as the very powerful 5.2cm that did 850 m/s back in the early 1900s (!) with the same shell weight. Make a new gun around one or both of the two ammo types, use the same pattern of ammo and there is even a bonus in that a decent HE shell is available.

France and UK - there are 47mm 'Hotchkiss' guns of decent MV, that can penetrate pretty much the same armor that the 2pdr can pierce, let alone the 25mm. British even have the more potent 3pdr Vickers. Again, make new guns in order to take advantage of new metalurgy.
Later, British Army can piggy back on the modern RN's 6 pdr (yes, we lose a few mm of penetration vs. the known 6pdr ATG, but the gun can be in the units by the time the war is declared), while French can have the modern 75mm gun that uses the widely-available ammo.
British can go with the new (for the 1930s) 75-76mm AA guns by Vickers as the new step, and have a potent AT gun couple of years before the historical 17 pdr is there. Again, the lower penetration figures are more than balanced-out by the earlier availability.

Italians - they can recall the 66mm guns from the war booty A-H ships, that might be still in some warehouse by the mid 1930s, together with the ammo? They have tried with the 65 mm as the high velocity AA gun that went nowhere. The 47mm Bohler was, IMO, a pretty sensible choice as far as the light AT guns go, but there was no follow up. Another not-that-heavy gun that might've been much more useful had it been manufactured in greater quantities was the 75/32, that perhaps shows how the French 75 of modern layout might've looked like.
The HEAT shells seem to be popular with the Italians, outfitted with these even the older 75mm pieces, as well as on the modern 75/18 howitzer.
The top-end weapons - 75 and 90 mm based on the new AA pieces - surely do look attractive, but Italian industry was ill able to manufacture more modern and expensive pieces in the required quantities.

 

[z42]

~75mm (medium or higher velocity) tank guns were somewhat revolutionary when they arrived on the scene. Not because the anti tank performance was somehow unexpected compared to what one would expect from an extrapolation of previous smaller tank guns, but because it was finally big enough that it was useful for shooting at soft targets as well. Which meant you didn't need separate vehicles for shooting at other tanks vs other targets.

I wonder if you could use the same argument for 75mm AT guns as well, combining the functions of the AT gun and infantry gun? I would suspect the benefit from such a dual purpose gun would be less than for tank, due to the higher importance of reducing weight to someone keep it mobile. So you might be better off with separate AT and infantry guns, if it allows each individual gun to be lighter?

 

[tomo pauk]

I wonder if you could use the same argument for 75mm AT guns as well, combining the functions of the AT gun and infantry gun? I would suspect the benefit from such a dual purpose gun would be less than for tank, due to the higher importance of reducing weight to someone keep it mobile. So you might be better off with separate AT and infantry guns, if it allows each individual gun to be lighter?

Some armies used the infantry guns widely, like the Soviets, Germans or Japanese. The Western armies seldom used these.
Infantry guns were usually under 500 kg, while the 75/76mm AT guns, or even the multi-purpose guns like the ZiS-3 or the pak 97/38 went easily above 1000 kg (make it 2000 kg for the lash-ups - you know who you are ).

A path less traveled might've been the breech-loading mortar, at least in the role of the infantry gun. Does not need to be as refined as the PAW 600, but it might be easier and cheaper to make since it does not need the rifled barrel, and can use cheaper ammo that still packs a lot of HE. The HEAT ammo is a 'natural' AT ammo for this. If in 82 mm, it can use the stocks of captured mortar ammo.

 

[EwenS]

British had the plans for their 57mm drawn up in 1938/39 and again, left them in the draw until they thought they needed them.

That was only part of the story. Yes the prototype was tested in 1939. Yes it did not enter immediate production. But the 2pdr was perfectly capable of dealing with all the German tanks in service in 1939/40. It could defeat 42mm of armour at 1,000 yards at 30 degrees. The Panzer III had max 30mm of armour (uprated in the Ausf H and later versions from late 1940). Panzer IV again 30mm (only uparmoured from late 1940). Plenty of the earlier versions still fought in NA in early 1941.

Britain lost 509x2pdr and 98 25mm Hotchkiss AT guns in France in 1940 and when they took stock in early June there were only 333 left in total of which just 167 were in Britain (the others were with units overseas in places like the Middle East, India, Malaya etc). Add to that there was an increasing demand from a growing Army. So the choice was:-

1. increase production of the 2pdr which was already underway and with which the troops were familiar and which could still tackle most threats. Production increased from 47 to 83 per month between Sept 1939 & June 1940; OR
2. have a hiatus in production while factories geared up to produce the 6pdr. There was estimated to be a 6-8 month delay in getting these new guns and then the problem of retraining the Army to use them.

So with the threat of invasion looming, it is hardly surprising that they chose to keep the 2pdr in production & service in the short term.

An order was placed in June 1940 for 400x6pdr to be fulfilled once the immediate demand for 2pdr had been satisfied. Production finally started in Nov 1941 and within 6 months they were leaving the factories at a rate of 1,500 per month. It could initially punch through 74mm of armour at 1,000 yards at a 30 degree angle (it was improved later)

 

[Shortround6]

A lot of the old naval guns were heavy due to old metallurgy/constructing methods.
Navy didn't care. an extra 100-200kgs on a 10,000 ton ship didn't matter.
That said some armies (Looking at the British here) shot themselves in both feet, one knee cap and one elbow with their doctrine/tactics and then complained they couldn't crawl well let alone walk/run.
Everybody knew how to make APCBC projectiles, at least big ones. They tried to go cheap, as long as you enemies used thin armor you could get away with cheap projectiles (and small cheap guns)

There were not enough old naval guns in decent shape to equip armies with. They could be used as models/examples but since you have to make new barrels, recoil systems and ammo anyway, just make what you want using some of the old tooling.
Trying to adapt old guns just means redoing a lot of things (changing something by 10-15mm) when the new barrels show up.

 

[Shortround6]

Some armies used the infantry guns widely, like the Soviets, Germans or Japanese. The Western armies seldom used these.

In some cases this was tradition/tactics/communications.
Infantry commanders (battalion/regiment) liked to have some firepower of their own so they wouldn't have to "ask" higher commands for fire support.
Lack of forward artillery observers. Lack of radios/field phones, High command husbanding ammo for later use or using the guns to support the other flank when the request was made.
Or other reasons. In general armies with better communications didn't rely on infantry guns as much although it was a narrow thing. There were a lot of requests and even some manufacture but issue of such guns was small. British built several hundred of these.

Used the same ammo as the 95mm howitzers in the British tanks. Never issued to the infantry. In part due to man power shortages.

A path less traveled might've been the breech-loading mortar, at least in the role of the infantry gun.

This gets dicey. If you hare using a rifled tube things get expensive. If you don't use a rifled tube you loose accuracy and you need a lot more ammo to take out point targets.
How many infantry men are pulling guns/toting ammo for the infantry guns instead of using LMGs/rifles in the rifle platoons/companies?
Sometimes the guns were offered but the infantry units were not going to get added men to man the guns.

 

[Shortround6]

That was only part of the story. Yes the prototype was tested in 1939. Yes it did not enter immediate production. But the 2pdr was perfectly capable of dealing with all the German tanks in service in 1939/40. It could defeat 42mm of armour at 1,000 yards at 30 degrees. The Panzer III had max 30mm of armour (uprated in the Ausf H and later versions from late 1940). Panzer IV again 30mm (only uparmoured from late 1940). Plenty of the earlier versions still fought in NA in early 1941.

The 2pdr was the best of the "small" AT guns (under 45mm). Then they stuck it with cheap projectiles and no HE ammo.
They also stuck it on the most expensive carriage ever built for a small AT gun.

360 degree traverse in case the enemy tanks showed up from an unexpected direction. The shield was large, the 3 legs added to effort to dig in.
It weighed almost twice as much as some other 37mm guns.
The gun was very good.
The ammo was cheap.
The carriage was expensive, heavy and overly complicated.

 

[herman1rg]

German 88mms (8.8 cm Flak 18/36/37/41) performed quite well as AT guns in various theatres

 

[tomo pauk]

Used the same ammo as the 95mm howitzers in the British tanks. Never issued to the infantry. In part due to man power shortages.

At 1000 kg, it was not the infantry gun anymore

This gets dicey. If you hare using a rifled tube things get expensive. If you don't use a rifled tube you loose accuracy and you need a lot more ammo to take out point targets.

Yes, the rifled guns were more accurate. While the PAW 600 landed 50% hits at 500m at 70x70 cm target with HEAT shell @ 520 m/s MV, the Pak 40 landed 50% of the hits at 500 m at the 20x30 cm target with AP shot 755 m/s MV (static targets??); source 'Waffen revue' No.82.

How many infantry men are pulling guns/toting ammo for the infantry guns instead of using LMGs/rifles in the rifle platoons/companies?
Sometimes the guns were offered but the infantry units were not going to get added men to man the guns.

Infantry guns were operated by dedicated operators, whose main weapon were their artillery guns. Same with mortar crews, AT gun crews etc.
Here the much lighter mortar ammo can be very handy, so biting the bullet and making a breech-loading rifled mortar will still be a good saving vs. the 75mm infantry gun.

The 2pdr was the best of the "small" AT guns (under 45mm).

Let's not discount the 47mm guns as the small AT guns. They were either lighter, or much lighter than the 2pdr, while offering equal or better penetration, and while also being outfitted with HE shells for self-defense against infantry.

Then they stuck it with cheap projectiles and no HE ammo.
They also stuck it on the most expensive carriage ever built for a small AT gun.

Bingo.

360 degree traverse in case the enemy tanks showed up from an unexpected direction. The shield was large, the 3 legs added to effort to dig in.
It weighed almost twice as much as some other 37mm guns.
The gun was very good.
The ammo was cheap.
The carriage was expensive, heavy and overly complicated.

Seems like people were not aware of the deployment nature of the AT guns, where the batteries are deployed, not one gun per a kilometer. Traversing 360 deg means that the own guns can be shot in the friendly fire, as well as the own truck etc. Also, seems like there was no test of how fast the 'normal' split carriage (that will be very light for a 40mm gun) can be re-directed.

 

[EwenS]

As for the 2pdr carriage, it comes back to the requirement. From Ian Hogg's "Allied Artillery of World War Two" with my emphasis.

"As in the early 1930s, the prime requirements for an anti-tank gun, once sufficient penetration was assured, were a firm platform and a fast, wide and smooth traverse, to allow rapid switching between target and tracking of a moving target. The 2-pounder Mark 9 on Carriage Mark 1, designed by Vickers, was given a three legged platform, one leg of which formed the towing trail, and the other two folded up for travelling. A sprung axle carried two wheels on brackets, so that once the gun was positioned, the three legs were placed on the ground and the wheels swung up off the ground. Screw jacks at the end of the three platform legs could then be operated to level the equipment. The gun could then traverse through 360 degrees, to cope with targets from any direction; the traversing mechanism had a two-speed gear, allowing a very fast movement to pick up targets, and a slower one for following and aiming at moving targets. On top of it all was a superlative telescope sight."

A cheaper Mark 2 carriage and easier to produce was similar to the above, except that the wheels were removed when placed on its ground platform. Both could be fired from their wheels but with less traverse available.

 

[Shortround6]

There were also side shields that offered over 270 degree protection for the gunner. Rarely or never used in action.
In the mid 30s such little "turrets" could have been devastating to fleets of thin skinned tankettes armed with machine guns.
Once tanks started firing rounds that could penetrate the thin shields or fire HE ammo (even mediocre hand grenade size) such deployment/emplacement had had it's day.
A simpler/ lighter carriage that offered 60 degrees or more of travers and needed less room to dig in might have made a difference.
The British 2pdr was the Rolls-Royce of light AT guns.
What was needed was something closer to a 4.5 liter Invicta

souped up Meadows truck engine. A close relative of the engines used in the early British light tanks.

 

[SaparotRob]

Beautiful car.

 

[Shortround6]

At 1000 kg, it was not the infantry gun anymore

except that the Germans had that 15cm infantry gun

Yes, the rifled guns were more accurate. While the PAW 600 landed 50% hits at 500m at 70x70 cm target with HEAT shell @ 520 m/s MV, the Pak 40 landed 50% of the hits at 500 m at the 20x30 cm target with AP shot 755 m/s MV (static targets??); source 'Waffen revue' No.82.

thank you. The smooth bore needs about 8 times the target area to land 50% of it's shots. The rifled gun may get 95-100% of it's shots into the target area of the smooth bore gun.

Infantry guns were operated by dedicated operators, whose main weapon were their artillery guns. Same with mortar crews, AT gun crews etc.

I may not have stated things clearly. Assuming an infantry battalion has 580 men and somebody offers the commander 3 inf guns but no extra men the commander has to take 18-24 men out of his rifle companies (or mortar platoon) to man the guns, deal with the transport and handle communications. And at least one officer.
Now if somebody offers the commander the 3 guns and around 20 men (trained) to go with them we may get a different answer from the commander.

Let's not discount the 47mm guns as the small AT guns. They were either lighter, or much lighter than the 2pdr, while offering equal or better penetration, and while also being outfitted with HE shells for self-defense against infantry.

The 45mm and up guns are generally in a different class than the small guns. There are a few cross overs. And the significantly larger HE shells made them more useful as infantry guns. The British 2pdr and the French 25mm may have been the ONLY AT gun/s that did not have an HE shell.

 

[tomo pauk]

except that the Germans had that 15cm infantry gun

Fair enough

The 45mm and up guns are generally in a different class than the small guns. There are a few cross overs. And the significantly larger HE shells made them more useful as infantry guns. The British 2pdr and the French 25mm may have been the ONLY AT gun/s that did not have an HE shell.

It was not the fault of 45-47mm AT guns that the 2pdr was overweight.

 

[Frog]

deleted

 

[Shortround6]

Fair enough



It was not the fault of 45-47mm AT guns that the 2pdr was overweight.

No it is not. That is squarely on the British.

The 45-47mm guns do cover quite a range, the Austrian/Italian Bohler gun might have got down to under 300kg (?) while the French 47mm was about 1070kg in action.
Powerful but slightly heavier than the German 50mm Pak 38.

 

[yulzari]

That was only part of the story. Yes the prototype was tested in 1939. Yes it did not enter immediate production. But the 2pdr was perfectly capable of dealing with all the German tanks in service in 1939/40. It could defeat 42mm of armour at 1,000 yards at 30 degrees. The Panzer III had max 30mm of armour (uprated in the Ausf H and later versions from late 1940). Panzer IV again 30mm (only uparmoured from late 1940). Plenty of the earlier versions still fought in NA in early 1941.

Britain lost 509x2pdr and 98 25mm Hotchkiss AT guns in France in 1940 and when they took stock in early June there were only 333 left in total of which just 167 were in Britain (the others were with units overseas in places like the Middle East, India, Malaya etc). Add to that there was an increasing demand from a growing Army. So the choice was:-

1. increase production of the 2pdr which was already underway and with which the troops were familiar and which could still tackle most threats. Production increased from 47 to 83 per month between Sept 1939 & June 1940; OR
2. have a hiatus in production while factories geared up to produce the 6pdr. There was estimated to be a 6-8 month delay in getting these new guns and then the problem of retraining the Army to use them.

So with the threat of invasion looming, it is hardly surprising that they chose to keep the 2pdr in production & service in the short term.

An order was placed in June 1940 for 400x6pdr to be fulfilled once the immediate demand for 2pdr had been satisfied. Production finally started in Nov 1941 and within 6 months they were leaving the factories at a rate of 1,500 per month. It could initially punch through 74mm of armour at 1,000 yards at a 30 degree angle (it was improved later)

In the real world of the time the infantry wanted a truly man manhandle able AT gun and the 2Pounder was adequate and much more easily man handled than a larger weapon but conceived solely as a AT gun.

The armoured people wanted a new tank gun that was AT capable and it would be nice to have an HE capability. The Treasury noted that the 2 Pounder would let a new tank kill another new tank quite easily and saw no reason to pay for yet another tank gun as well as the new infantry 2 Pounder and the smoke/HE job could be done with the existing mountain howitzer so would not finance the putative 6 Pounder so the design lay on the shelf until the fiancés allowed for it. Then came the BoF……