Tank & AFV armament alternatives, 1935-45 (1 Viewer)

[Shortround6]

US 37mm with the initial ammo was indeed worse as a hole puncher.
British did go anyway with a very big tank at the time, adding another gun to toss around smoke shells.
I have nothing against making better ammo.

Agreed

while the accuracy even under combat conditions was supposed to be very good.

Germans may have gotten good groups (small deviation) with their 75mm, American 75 How may have been very good too. The problem is putting the group on target at long range and not putting shots under and over and finally getting a hit with the 3rd, 4th or 5th shot. The flatter shooting HV gun may get a hit with the 1st or 2nd shot at the same distance.
German used a better sighting system, it needed better training but the result was a lot better shooting at long range. There were a number of different models but most used this system.

which worked like this.

In combat getting exact 90 degrees and using decimal points are both going to be rare but
the short barrel MK IV also helped with

range scales for 3 different ammo types and in the real sight there were indicators on the scale for the current elevation of the gun, Gunner put the top of the big triangle just under the target at all ranges.
British gunner got cross hairs, little or nothing to estimate range with and had to put the cross hairs on or over the target based on his judgement. Now at close range and trying to fire on the move the British system was quicker. At longer range it used up a crap load of ammo per hit. In took until late 1942/early 1943 for the British to do the 180 degree turn and go to firing from the halt but most/all of their tanks still had the old telescopes/sights.
Prewar tank gunnery training/standards went right in the toilet after the Battle for France and the rapid build up of the British army.

 

[Shortround6]

From a website on British Artillery:

OTHER FIREPOWER

Brief description of other artillery firepower, mortars, naval gunfire, air OP (AOP), arty/R and offensive air support used by the British in World War 2

nigelef.tripod.com

Initially anti-tank guns were limited to armour piercing ammunition. However, in early 1944 HE ammunition was authorised for direct fire tasks. The concern had been that too much HE would mean too much wear to the anti-tank guns and consequently lose accuracy for their anti-tank role. The HE ammunition scale was:

6-pdr​	up to 25%​	1st line 96 rpg, all types
17-pdr​	up to 5%​	1st line 90 rpg, all types
3-in M10​	up to 30%​	1st line 90 rpg, all types

This led to anti-tank guns increasingly used in their secondary role for direct fire against hard targets such as bunkers, 'pill-boxes', MG posts, snipers in houses, OPs, etc. In effect a similar role to assault or infantry guns in other armies. This first happened in N Africa at the beginning of 1941 using 37-mm Bofors. However, 'concrete busting' with 17-pdr became fairly usual in Italy and 3-inch M10s were also found to be very useful for dealing with strongpoints such as houses or bunkers. Other uses included troops behind light cover, soft skinned vehicles, nuisance harassing fire and cutting wire obstacles.

So we have the British using borrowed 37mm AT guns with HE ammo but their own 2pdrs were useless?
I think there has been a lot of CYA (cover your A$$) with some of these accounts of 2pdr/6pdr HE usage.

 

[Greyman]

Soviets must have been using better explosives in their 45mm tank and AT guns HE shells.

I'm no expert, but I see one difference right off the bat.

 

[yulzari]

articles/books say the HE showed up in 1943 and was used in armored cars. In fact it is often stated that the armored cars which had been fitted with Little John muzzle devices (Squeeze bore) for better AP often left them off the barrels so they could fire HE when/if needed. Apparently the armored car crews did not think the HE was useless?

They had found that the tungsten core of the Littlejohn rounds allowed nearly as good penetration without the adaptor as with so leaving them off allowed the option of HE. Which did something at least to soft targets like lorries and river barges.

 

[z42]

For my money, British making more and improved infantry tanks instead of the cruiser tanks is more than okay.

Ignoring the gun for a second, historically the British concept of the 'universal tank', later MBT, developed from the 'heavy cruiser', but I suppose with enough butterflies frantically flapping their wings, it could instead have developed from a 'fast infantry tank'.

Or maybe not; it's easy enough to argue that a cruiser tank could use more armor, but a faster infantry tank has the obvious objection that infantry can't run any faster than they already do, so what's the point?

 

[z42]

In the 1930s a lot of countries didn't know what the best solution/s were. It took quite a while (1945?) to arrive at point where most people agreed, 4 man crew, no bow gun, one big (or biggish gun) single co-ax gun and a few other things like good vision and good radios.

The disappearance of the bow gunner might also have to do with the bow gunner doubling as radio operator? As radios became better and easier to use, the commander could handle the radio himself, and the bow gun and gunner only by himself added so little extra combat capability that it wasn't worth keeping him around?

 

[Shortround6]

The disappearance of the bow gunner might also have to do with the bow gunner doubling as radio operator? As radios became better and easier to use, the commander could handle the radio himself, and the bow gun and gunner only by himself added so little extra combat capability that it wasn't worth keeping him around?

It varied somewhat depending on country and year. British almost always had the radio in the turret. If it needed an "operator" (needs code key) sometimes the loader did it. The M3 Grant tank had a turret to British spec and had the radio in the turret in the larger bustle. The M3 Lee (US version) had the radio operator in the hull with no machinegun.

US seemed to have a real problem with what the commander was supposed to do.
Tell the driver where to steer to position the 75mm gun (and use the two bow machine guns)
Tell the 75mm gunner what target the commander wanted him to engage and what ammo to use.
Tell the turret gunner where to aim the 37mm gun/co-ax gun (and load the 37mm?) and what ammo.
Identify and engage targets using his own .30 cal machine gun.
Somehow tell the radio operator what messages the commander wanted to send or get messages from the operator in the hull up to the turret top.
As a tank commander see where his platoon mates were and not get ahead or behind.

Once tanks started using voice radio things got easier and the British just figured it was easier for the tank commander not to have have an extra step in the system.
Early British radios could only act as a radio OR an intercom at the same time. Did the commander want to talk to his crew or other tanks at a given moment. The No 19 set could do both at the same time. Commander could talk to other tanks while the crew could talk to each other.
Then we have the disconnect between what the crews were actually doing and what the tank designers and the guys on the tank boards thought they should be doing.
Crews were often operating short of crewmen. If the radio is in the turret the bow gunner becomes an extra man that can fill in due to casualties/sickness. Or you can fill the seat with extra ammo/food/water/ etc.
It's not like he can hit anything with bow gun anyway in some tanks.

Bow gun in a Sherman. There is no telescope or even a view port. There is a periscope that is higher than his head that he can observe tracer fire though from a gun that is near waist level on his body.
In the Firefly they yanked the bow gun out, plated it over and stuffed more 17pdr rounds in the space. Americans kept the bow gunner through the M-47 tank,
British canned it officially with the Centurion (at least after the first prototype or mock up?)
It was figured that the bow gunner took up about 35 cu ft of space inside the tank that could be used for other things (or make the tank smaller).

 

[EwenS]

In the M3 the radio operator sat immediately to the rear of the two fixed 0.3" MG, to the left of the driver, and one of his duties was to reload these with new belts.

The barrels protrude from 2 separate openings just to the right of the driver's position in the above photo and to the left of the headlight.

 

[EwenS]

Article here on Operation Sentry, the Centurion trials in May 1945

Operation Sentry - The First Centurion Trials 1945 - Tank Encyclopedia

The brand new A.41 Centurion needed to be troop tested for deployment against Nazi Germany, but the war ended too quickly.

tanks-encyclopedia.com

 

[Shortround6]

In the 1930s a lot of countries didn't know what the best solution/s were. It took quite a while (1945?) to arrive at point where most people agreed, 4 man crew, no bow gun, one big (or biggish gun) single co-ax gun and a few other things like good vision and good radios

The disappearance of the bow gunner might also have to do with the bow gunner doubling as radio operator? As radios became better and easier to use, the commander could handle the radio himself, and the bow gun and gunner only by himself added so little extra combat capability that it wasn't worth keeping him around?

For the British the sequence actually went something like this.
Light tanks......................................................................................Crusiers...........................................................infantry tank
2 man tanks no radios.................................................................A 9 RIT 6 men 2 bow guns........................A II Matilda I two men
MK V 1936, radio in turret gunner operator.......................A 10 RIT, 4-5 men.........................................A 12 Matilda II RIT 4 men No BMG
MK VI larger turret better radio?.............................................A13 I RIT, 4 men No BMG........................Valentine RIT, 3-4 men No BMG
MK VII Tetrarch 1938/39 radio in turret................................A13 II RIT, 4 men No BMG.........................A-22 Churchill RIT, 5 men BMG (or larger)
MK VIII Harry Hopkins radio in turret (RIT)..........................Covenanter RIT, 4 men No BMG
Last 4 are all 3 man crews. .........................................................Crusader RIT, 5 men bow gun
...............................................................................................................Cavalier RIT, 5 men bow gun
...............................................................................................................Centaur RIT, 5 men bow gun
...............................................................................................................Cromwell RIT, 5 men bow gun
...............................................................................................................Comet RIT, 5 men bow gun
...............................................................................................................Centurian RIT 4 men, No BMG

There was no reason for the British to use the bow gunner except for the love of machine guns and perhaps an extra man to share the maintenance duties (night guard?) with.
Other armies may have been different.

On the flip side of this one book claims (with nothing to back it up) that the War office was trying to get British tank makers to bid on tanks with the idea of paying 1000 pounds per ton of weight. Which helped lead to cheap tanks (thin armor) and low powered engines. But the cost of the bow gunner in terms of hull size must have been known to at least some people. A10 used the same running gear (suspension and drive train) as the A 9 and good part (but not all) of the extra weight of the thicker armor was compensated by getting rid of the two little MG turrets and replacing them with a single gun in the flat plate in front of the driver. The much heavier Matilda II did away with the hull gunner and bow gun and they don't seem to have been missed. Matilda II not seeing much combat until after the Churchill design was well in hand. Once they made the tank big enough to stick a 2nd cannon in the hull they had to use the space for something once they went back to one cannon per tank
A real missed opportunity for the British was the Crusader. As they made the tank bigger from the earlier cruisers they could have left the hull gunner and useless turret out and used the weight/space saved for either thicker armor to begin with or make the main turret bigger so it would be easier to stick a bigger gun in. The little turret had such poor ventilation it nearly killed the gunner when he fired the gun and he couldn't see well enough to be effective even if he could breath.
You still had the thinking that the true power of the tank was it's machine guns and the cannon was sort of an unwanted accessory, handy if the enemy showed up with tanks
Once the BMG showed up it had to stay for all the cruisers that followed until the size of the ammo for the 17pdr (and perhaps sanity) forced the hull gunner and BMG out of the tank.

 

[Frog]

For the British the sequence actually went something like this.
Light tanks......................................................................................Crusiers...........................................................infantry tank
2 man tanks no radios.................................................................A 9 RIT 6 men 2 bow guns........................A II Matilda I two men
MK V 1936, radio in turret gunner operator.......................A 10 RIT, 4-5 men.........................................A 12 Matilda II RIT 4 men No BMG
MK VI larger turret better radio?.............................................A13 I RIT, 4 men No BMG........................Valentine RIT, 3-4 men No BMG
MK VII Tetrarch 1938/39 radio in turret................................A13 II RIT, 4 men No BMG.........................A-22 Churchill RIT, 5 men BMG (or larger)
MK VIII Harry Hopkins radio in turret (RIT)..........................Covenanter RIT, 4 men No BMG
Last 4 are all 3 man crews. .........................................................Crusader RIT, 5 men bow gun
...............................................................................................................Cavalier RIT, 5 men bow gun
...............................................................................................................Centaur RIT, 5 men bow gun
...............................................................................................................Cromwell RIT, 5 men bow gun
...............................................................................................................Comet RIT, 5 men bow gun
...............................................................................................................Centurian RIT 4 men, No BMG

There was no reason for the British to use the bow gunner except for the love of machine guns and perhaps an extra man to share the maintenance duties (night guard?) with.
Other armies may have been different.

On the flip side of this one book claims (with nothing to back it up) that the War office was trying to get British tank makers to bid on tanks with the idea of paying 1000 pound per ton of weight. Which helped lead to cheap tanks (thin armor) and low powered engines. But the cost of the bow gunner in terms of hull size must have been know to at least some people. A10 used the same running gear (suspension and drive train) as the A 9 and good part (but not all) of the extra weight of the thicker armor was compensated by getting rid of the two little MG turrets and replacing them with a single gun in the flat plate in front of the driver. The much heavier Matilda II did away with the hull gunner and bow gun and they don't seem to have been missed. Matilda II not seeing much combat until after the Churchill design was well in hand. Once they made the tank big enough to stick a 2nd cannon in the hull they had to use the space for something once they went back to one cannon per tank
A real missed opportunity for the British was the Crusader. As they made the tank bigger from the earlier cruisers they could have left the hull gunner and useless turret out and used the weight/space saved for either thicker armor to begin with or make the main turret bigger so it would be easier to stick a bigger gun in. The little turret had such poor ventilation it nearly killed the gunner when he fired the gun and he couldn't see well enough to be effective even if he could breath.
You still had the thinking that the true power of the tank was it's machine guns and the cannon was sort of an unwanted accessory, handy if the enemy showed up with tanks
Once the BMG showed up it had to stay for all the cruisers that followed until the size of the ammo for the 17pdr (and perhaps sanity) forced the hull gunner and BMG out of the tank.

Notice that the tank BESA machine gun of Czech origin was firing the same 7,92 mm cartirdge as the Germans which theorically enabled using captured ammunition.

 

[Elan Vital]

For the British the sequence actually went something like this.
Light tanks......................................................................................Crusiers...........................................................infantry tank
2 man tanks no radios.................................................................A 9 RIT 6 men 2 bow guns........................A II Matilda I two men
MK V 1936, radio in turret gunner operator.......................A 10 RIT, 4-5 men.........................................A 12 Matilda II RIT 4 men No BMG
MK VI larger turret better radio?.............................................A13 I RIT, 4 men No BMG........................Valentine RIT, 3-4 men No BMG
MK VII Tetrarch 1938/39 radio in turret................................A13 II RIT, 4 men No BMG.........................A-22 Churchill RIT, 5 men BMG (or larger)
MK VIII Harry Hopkins radio in turret (RIT)..........................Covenanter RIT, 4 men No BMG
Last 4 are all 3 man crews. .........................................................Crusader RIT, 5 men bow gun
...............................................................................................................Cavalier RIT, 5 men bow gun
...............................................................................................................Centaur RIT, 5 men bow gun
...............................................................................................................Cromwell RIT, 5 men bow gun
...............................................................................................................Comet RIT, 5 men bow gun
...............................................................................................................Centurian RIT 4 men, No BMG

There was no reason for the British to use the bow gunner except for the love of machine guns and perhaps an extra man to share the maintenance duties (night guard?) with.
Other armies may have been different.

In the US, the bow gunner (or radio operator in M10 TD since no bow MG) also had duplicated controls to work as assistant driver, although experience demonstrated that this was not an essential position and that replacing the fatigued crew would do the job.

During WW2, US industries and some officers (including British liaison) recommended doing away with the bow MG at least on certain designs (T14 especially) as it complicated manufacture of the front plate and introduced a structural weakpoint in the armor, while being of little combat value.

In the Soviet Union, the bow MG was used on T-34 and KV but was replaced with a single fixed MG operated by the driver on the T-43, T-44 and T-54 (and no MG from T-55A onwards IIRC) as well as the IS series (when it was not absent).

In pre-Fall France, bow machineguns were only present in fixed form on the Char D, Char B and requested (twin fixed mount) for the G1, but was absent from light and cavalry tanks, in spite of the battle tanks and the Somua having a hull radio operator to better use the telegraphic mode of the radio. Ball mounts were IIRC only present on the experimental fortification assault tanks and on the AMX entry for the future battle tank (on the sides, and rear for the former for coverage of gaps).

In the UK, P.M. Knight reports in his books on A13 and Crusader that:
- A9 initially started out with fixed machineguns rather than turreted ones and that this (or alternatively A10 style) was briefly considered for an extra simplified A9.
- A10 started out with no MGs when it was a light Infantry Tank (same as Valentine and both Matildas)
- Crusader was contemplated both during development and in 1941-42 with an A10/Cromwell style layout. Colonel Davidson noted prewar that machinegun turrets were a bigger weight penalty when armored at 30mm and more and that the extra arc of fire was no longer as important as when the Medium Tanks and then Heavy Cruisers were mooted with auxiliary turrets.
It certainly would have been a highly useful change as it would have removed the need to modify Crusader in the field with a cover plate and no auxiliary turret, which left a weakpoint in the armor (and probably simplifies and even improves the front armor layout even with the BESA mount, while possibly saving a little weight).

That said, the auxiliary turret is not really at fault for the late armor upgrade to Crusader. The tank as is could accomodate the extra weight, but for unclear reasons trials with ballast weights was not pursued at the required pace and there was much more focus on fixing the automotive issues. 60mm of armor was recommended for Cruiser tanks back in late 1940, and Covenanter tested ballasts for 60mm of front armor (however the opportunity was not taken to include extra armor weight in the design of the strengthened suspension in Covvie Mk III).

Both Crusader and Covenanter also weren't reworked for single plate hull front construction (such a setup, with increased armor basis to boot, was mooted for Crusader but in 1942 IIRC and was done on Cromwell), which would have improved the ballistic value of it and also removed some weakpoints (Crusader did not meet its 40 then 50mm-thick armor basis everywhere, both on a geometric and penetration velocity standpoint).

 

[bf109xxl]

In the Soviet Union, the bow MG was used on T-34 and KV but was replaced with a single fixed MG operated by the driver on the T-43, T-44 and T-54 (and no MG from T-55A onwards IIRC) as well as the IS series (when it was not absent).

The unfortunate driver - it was not enough for him to operate the levers with a force of tens of kilograms, but also to operate the MG in between. No, that's enough to overload the driver, let's leave the bow MG to the radio operator. But there was another machine gun in the turret - it was paired with a gun. T-44 had also two MGs, whereas T-54 got three MGs in the early variants, in the later ones the number of MGs was reduced by one. Turret MG remained on the T-55A as well. IS had three MGs, IS-3 only one in the turret.

 

[Shortround6]

Going back to the earlier statement.
"In the 1930s a lot of countries didn't know what the best solution/s were. It took quite a while (1945?) to arrive at point where most people agreed, 4 man crew, no bow gun, one big (or biggish gun) single co-ax gun and a few other things like good vision and good radios.
(1945?) to arrive at point where most people agreed
4 man crew
no bow gun
one big gun
good vision
good radios

we have 5 things, In 1939 the British had 2 of them (crew size and no BMG) and were working on 2 (vision and radios) and we are disagreeing about the 5th (big gun) although this is debatable. Compared to the .5in gun the MK VI light the 2pder was huge
A problem I have with the British is that they went backwards on the Crew size, the BMG and Vision while not going forward with the gun size until 1942 and the improved radios were the only bright spot. Engines/reliability certainly did not improve.

Everything is relative and the French well and truly sucked with one man turrets, crew size, lack of vision, few and poor radios. Granted they didn't have bow guns but having that plus doesn't make up for all the bad stuff. Yes the long French 47 tank gun (not AT) could fire HE but since it didn't out perform the 2pdr as an AT gun at 400-500meters it obviously had problems.
In 1939 the Germans had problems of their own, without going though the list of German tanks the only ones that count in 1939 are the MK III and MK IV and they had crap armor (14-15mm) 5 man crew BMG (sometimes) big gun (only on the MK IV) good vision and good radios. They also invaded Poland with just 96-98 MK IIIs.

For now we can pass over the Americans the M2A4 light tank didn't enter production until May 1940.
Italy is building the M11/39 and had no features we are looking for.
Japanese have very little in production with good features (or features that lead to 1945 goals)
Soviets don't have much in production, they skip over the sweet spots with the T-28 (way to big/complicated) and the BT-7 and T-26 good guns but 3 man crews have problems.
The Early T-34s in 1940 have poor vision, poor radios (those that had them), had the BMG but that is were the 4th man was, not helping with the main gun which was the tanks reason for being.

The British were on the Path at least as well as anybody else. Then they went off the path and fell in the canal. The radios got better. Instead of fixing/improving the vision/cupolas they took them off and eliminated view ports/vision slits but did not replace them with much. If you can't see you can't shoot, or drive. British actually had one of the best tank machine guns of the war. Other countries needed 2-3 machine guns to get decent effect. The British could get good effect with one gun. Most BMGs had crappy sights or sight arrangements and did not give good results compared to the same gun in the main turret. Granted the British did not have a lot of tank combat experience in France or in North Africa (Matilda's vs tankettes doesn't tell you much.)
Just slinging in a bigger gun doesn't solve any of these problems. Look at the early T-34s in Russia. They had stuffed 76mm guns in a turret designed for a 45mm gun. Yes they had the 76mm guns but they had a very bad rate of fire. 5 rpm on a test range? 2-3 rpm in actual combat?

 

[tomo pauk]

Everything is relative and the French well and truly sucked with one man turrets, crew size, lack of vision, few and poor radios. Granted they didn't have bow guns but having that plus doesn't make up for all the bad stuff. Yes the long French 47 tank gun (not AT) could fire HE but since it didn't out perform the 2pdr as an AT gun at 400-500meters it obviously had problems.
In 1939 the Germans had problems of their own, without going though the list of German tanks the only ones that count in 1939 are the MK III and MK IV and they had crap armor (14-15mm) 5 man crew BMG (sometimes) big gun (only on the MK IV) good vision and good radios. They also invaded Poland with just 96-98 MK IIIs.

The job of the French tank gun (as it was the case with other people's tank guns) of 47mm was to outperform the armor protection of the enemy tanks. In that, it was more than suitable for the job.
It was also better than the 37-40mm guns of the day wrt. the HE performance.
The Pz-IIIE and F were with 30mm armor (bar the belly and roof plates), not with only 14-15mm. None of the earlier versions went West in 1940.
Similar was the Pz-IV situation, that has gotten the 30mm armor in the front by 1939.

Germans saw that the Polish were tackling their very early tanks with 20mm guns and by the Maroszek AT rifles, so the decision to move to 30mm was prudent, but also underwhelming - even the small 37mm AT guns will still have a field day with these tanks.
There is no doubt that German tanks needed to be even more armored, and outfitted with the guns that made much more oopmh than what they were installing in 1938-41. The armor upgrade was being done by 1940/41, but guns' upgrade was lagging in a significant fashion, despite the 5cm guns for the Pz-III.

Italy is building the M11/39 and had no features we are looking for.

The whole Italian tank & AFV program will be needing the complete overhaul, and ASAP.

 

[Shortround6]

The job of the French tank gun (as it was the case with other people's tank guns) of 47mm was to outperform the armor protection of the enemy tanks. In that, it was more than suitable for the job.
It was also better than the 37-40mm guns of the day wrt. the HE performance.

True but the French 47mm had very little stretch. Most other tanks didn't have much stretch either. Higher velocity guns are easier to hit with at 600-1000 meters range. Remember that the projectile will drop 16ft (4.88 m) in it's first second of flight. yes you set up the gun so it hits a little high in the first 200-400meters so you can still hit in the last parts of the 1st second or even the first 1/10 or 2nd tenth of the 2nd second of flight. The projectile will fall 48ft (14.63m) in the 2nd second of flight.
French were also loading 37mm guns of differing abilities in a lot more tanks per month than they were loading 47mm guns into. They were certainly using more of the HV (700ms) 37mm guns in the last few months though.
Germans and French also tended to 'cheat' and used lower velocity HE shells with larger HE content that the British and Americans used later. Americans and British were going for easier training (use the same aiming point/procedure).

The Pz-IIIE and F were with 30mm armor (bar the belly and roof plates), not with only 14-15mm. None of the earlier versions went West in 1940.
Similar was the Pz-IV situation, that has gotten the 30mm armor in the front by 1939.

Such was progress win 1939-40-41. What was acceptable in June of 1939 was not acceptable in October and what was acceptable in April of 1940 was not acceptable in July of 1940. Same in 1941, what was acceptable in May 1941 was not acceptable in Sept/October 1941.

There is no doubt that German tanks needed to be even more armored, and outfitted with the guns that made much more oopmh than what they were installing in 1938-41. The armor upgrade was being done by 1940/41, but guns' upgrade was lagging in a significant fashion, despite the 5cm guns for the Pz-III.

Germans had started development of the 5cm/L42 in 1938. It was not done in response to either Poland or France.
Germans (and others) did not want to use long, high velocity tank guns because they were afraid that the guns, when rotated to the side, would get wacked against trees, power poles, building and other obstacles, with varying degrees of damage to gun, vehicle and crew. Getting shot by enemy tank with superior gun soon changed the priorities.

 

[yulzari]

How does the M3 Lee fit into the discussion on bow machine guns? The British Grant was satisfied with the turret co axial whilst the Americans stuck a machine gun turret on top of a tank turret on top of an already high casement gun hull.

 

[tomo pauk]

True but the French 47mm had very little stretch. Most other tanks didn't have much stretch either. Higher velocity guns are easier to hit with at 600-1000 meters range. Remember that the projectile will drop 16ft (4.88 m) in it's first second of flight. yes you set up the gun so it hits a little high in the first 200-400meters so you can still hit in the last parts of the 1st second or even the first 1/10 or 2nd tenth of the 2nd second of flight. The projectile will fall 48ft (14.63m) in the 2nd second of flight.

Make a cored ammo and see what it does for you. On the German short 5cm gun, APCR was adding almost 400 m/s when compared with the APCBC (685 m/s). Soviet 45mm M1932 and 37 were also no great shakes, 760 m/s with full-weight AP ammo, and the APCR shot upped the MV by 310 m/s, and penetration by a good margin and up to 1000m.

Germans and French also tended to 'cheat' and used lower velocity HE shells with larger HE content that the British and Americans used later. Americans and British were going for easier training (use the same aiming point/procedure).

If it is a fair fight, you've done something wrong

Such was progress win 1939-40-41. What was acceptable in June of 1939 was not acceptable in October and what was acceptable in April of 1940 was not acceptable in July of 1940. Same in 1941, what was acceptable in May 1941 was not acceptable in Sept/October 1941.

Agreed.

Germans had started development of the 5cm/L42 in 1938. It was not done in response to either Poland or France.

You are right. I should've worded my post better there.

Germans (and others) did not want to use long, high velocity tank guns because they were afraid that the guns, when rotated to the side, would get wacked against trees, power poles, building and other obstacles, with varying degrees of damage to gun, vehicle and crew. Getting shot by enemy tank with superior gun soon changed the priorities.

Again agreed. Although the Germans with the short 75mm went a bit overboard there, even when these precautions are taken into consideration.
A hotter loading of the 75mm cannon (for another 100 m/s perhaps) would've still worked with such the short barrel, though.

 

[Frog]

How does the M3 Lee fit into the discussion on bow machine guns? The British Grant was satisfied with the turret co axial whilst the Americans stuck a machine gun turret on top of a tank turret on top of an already high casement gun hull.

The inspiration from the French B1 / B1bis : a huge hull with a heavy gun gun and a turret with a cupola on top, without MG in this case.

 

[Shortround6]

Yep, the US saw the Char B 1 and said "If a two story tank is good, a 3 story tank has got to be better!"