Alternative light and anti-tank guns, 1935-45

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Penetration goes up with the square of the speed. 10% more veleocity means 21% more penetration in theory.

According to the de Marre formula, it is more like V^1.4283, or Ek^0.714.

The HEAT round at 4.54kg was fired at 450m/s.
The Pak 40 fired a very similar projectile at 450m/s also.
The 8cm PAW fired a 2.70kg HEAT projectile at 520m/s.

The muzzle velocity of 450 m/s was a limitation caused by rotation.
The PAW600 was limited by the muzzle energy resulting from the gun's mass.

US had tested the T45, a HVAP for the M3 75mm gun.
8.4 lbs/3.8kg projectile at 2870fps/870m/s
116mm penetration at 500 yard with 30 degree plate

Interesting - 1.4MJ of muzzle energy. The cartridge probably had a very shallow bullet seating, therefore a larger amount of powder.

A few posts ago in this thread, I've suggested that the small gas divert tube is added to the small AT gun so the recoil is lowered, since part of the high-speed gasses is pushed backwards. That again means that the whole gun can be lighter due to the lower stress exerted on the weapon. Sorta 10% recoiless gun.

A very stupid idea - introducing the main utility disadvantage of a recoilless weapon (backblast) without tactical advantages (weapon with minimal mass). In addition, it causes a rather significant loss of muzzle energy.

RT-20 was supposedly doing 850 m/s, despite the short barrel and the divertion of small % of the gasses.

Do you believe in fairy tales?
Using the same cartridges as the M55, the rifle achieves the same muzzle velocity with a barrel that is half as long with a gas bleed?
2/3 of the length of the Polsten barrel...

 

[tomo pauk]

A very stupid idea

I wish you all the best.

 

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I wish you all the best.

It's nothing personal. Stupid ideas deserve an honest assessment. The lack of feedback deprives you of information when you should have thought twice, making it impossible to improve.
Crazy ideas might work, stupid ones don't.

BTW, flooding the forum with ill-considered ideas is a form of trolling. If you like the game, fine, but expect direct criticism.

 

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HESH bypasses the 1st step and goes to the 2nd step, several pounds of metal flying around inside the tank.

But this does not work with any form of composite or space armor. Actual penetration is no greater than ~1.25x caliber.

The higher values mentioned, such as 400mm for 125mm guns, are the equivalent for heavily sloped monolithic steel armor - slope has minimal effect on hesh penetration in absolute terms.

How low might one go and still have a satisfying light AT gun that uses HEAT?

The best candidate is the 37mm SA 18 for obvious reasons, highly developed (by WWII standards) variants could achieve penetration of up to 50mm.
Earlier development of HEAT ammunition would be an excellent alternative to the SA 38, radically improving French AT capabilities.

The pre-war development of shaped charges fired from low-velocity guns would have hampered the development of tank armour, favouring more light and fast machines.