Shaped charge HL/B shell for M1897 gun

[pzgr40]

Cutaway model of a French 7,5cm High explosive shell for the famous M1897 field gun, converted into a shaped charge shell type B (HL/B) for the German army to change the field gun into an anti-tank gun.
The M1897 Field gun was –for it’s time – a very modern gun which set the pattern for future developments for many years to come. It used the Nordenfelt eccentic screw breech mechanism which gave the gun a maximum firing rate of 20 rounds per minute (12 rpm was the practical rate). The gun also used a very modern designed hydraulic recoil system, that allowed rapid fire without the need to lay the gun on it’s target after each seperate shot.
It has been in use with many countries and was still in use with Camerooon, Greece, Morroco, Mexico and Upper Volta in 1975. The original gun made use of spoked wooden wheels and Horse carriage, the later types made use of pneumatic tyres and was truck towed.

In 1940, the German army captured large amounts of the M1897 gun and took in in their own inventory as the Fk (FeldKanone / FieldGun) 231(f), but it was also known with the more common name Fk97(f). These guns were not only captured in large numbers in France and the French colonies in north Africa, but also in European countries like Poland that had obtained large numbers of these guns.
Initially, most of these guns were used in coastal defence.
2.854 barrels of the M1987 gun were made suitable to be placed in the gun carriage of the 5cm Pak 38 in 1942 to do service as an anti-tank gun. In 1943 another 858 followed. These guns were named Pak 97/38. Hundred and sixty barrels were made suitable to be placed in the gun carriage of the Pak 40 gun; these guns were named Pak 97/40.
The original French armour piercing projectile had a low Vo of 570 mtrs/sec, and therefore a low penetration of 75mm at 500 meters. Before WW2 this was more than adequate, but by 1942 this number was absolutely inadequate. The German army than decided to have 2,6 million high explosive shell to be send to Germany to have them converted into shaped charge shells to raise the armour piercing capacity to 90mm at 1500 mtrs. The projectile had a low Vo of 450 mtrs/sec, but that is rather an advantage than a disadvantage for a shaped charge projectile. Projectiles were converted to HL/A, HL/B (as described in this posting) and HL/C.

An interesting detail of the projectile is the nose cap. Normally with German WW2 shaped charge shells this is made from cast zinc, here it consists of a threaded steel ring to which a pressed sheet steel nose cap is attached. Clearly a simplification of the production process.

Another interesting detail is the shellcase of this cartridge; it is 350mm long and has an 85mm rim at the base.
When US troops arrived in France 1n 1917 to fight on the western front they hardly had any artillery brought in from the USA. This lack of artillery was solved by buying M1897 guns and ammo from the French army. In 1918, these guns were taken to the USA. The M1897 gun was further developed in the USA and was taken into service as the M3 gun in the M4 Sherman tank. The shellcase of the M3 Gun of the Sherman tank has …. as you can guess…. exactly the same dimensions as the M1897 gun shellcase. As the Sherman tank is an infantery support tank, a field gun as main armament was thought to be sufficient, it was not designed or intended to fight other tanks.

Regards, DJH.

[Bellifortis]

Merry Christmas @pzgr40,
thank you for this new nice handicraft of yours. This HEAT shell is an example of old type shells fuzed from the front with a spitback-fuze. Already during WW2 many experiments were made, regarding the fuzing of HEAT projectiles. It was recognised, that the fuze in the front had a very deliterous effect on the power of armourplate penetration. Since approximately the 1960s piezo-crystal elecric ignition system is almost exclusively used all over the world. Does anyone here has seen any experimental data on how bad (in % of degradation of performance compared to no fuzeobstruction up front) the fuze degraded the performance. The HEAT-jet has to penetrate the metalfuzebody first, before it can penetrate the armourplate. How many % of penetrationdepth (approximately) is lost in penetration of the fuzebody ?
Regards,
Bellifortis.

[MINENAZ16]

Thanks for sharing. Very interesting round.
It's the first time I see such a top shape.
Could you post a picture of the other side of the shell (uncutted face) ?
Thank you.

[Alpini]

They also existed with the normal solid zinc cap.

The french markings are often still present on these shells.

[pzgr40]

Hi minenaz16 and Alpini, here the backside of the long steel cap, and an example of the French shell with the zinc cap I made for member Greif about a decade ago

Regards, DJH

[Speedy]

Merry Christmas @pzgr40,
How many % of penetrationdepth (approximately) is lost in penetration of the fuzebody ?
Regards,
Bellifortis.

The problem isn't an penetration an front fuze - it's only some milimeters thick. First part of problem was a former type of front fuzen not like in HL/B, with detonator - a small explosive-filled tube protruding through shaped-charge conical inlet to the explosive charge. Anything solid inside of inlet seriously degrade process of forming "plasma-jet" of metal, that penetrated an armor. But HL/B has an different type of fuze, with micro-shaped-charge build-in, that put a small "plasma jet" through an empty tube to the detonator in the rear part of charge.

A second part of problem was IMHO a too short distance between an target and a shaped-charge inlet bottom. This distance is necessary for proper formed of "plasma-jet" and it is some diameters of inlet, 3-5, maybe up to 10. But in many early HEAT ammunition this distance is less than 1 diameter, so mainly for this reason the armor penetration was poor.