Cutaway model of a 37x57R bounding high explosive shell for the WW1 Austrial-Hungarian 3,7cm infanteriegeschutz (infantery gun) M15. This gun was meant for trench warfare, but was also very suitable for mountain warfare. One of the big problems with trench warfare were the enemy field fortifications that could hardly be defeated by direct or indirect fire from behind the battlefield. Towing big guns onto the battlefield unseen was quite impossible, also; the battlefields had often changed into a mudfield in which the heavier guns simply sunk away.
Therefore, a gun was designed that could fire a shell through the firing openings of the field fortifications from a relatively close range, but also was light enough to be carried over the battlefield disassembled in three pieces by three man (Barrel 34,6kg, carriage 25,3kg ; tripod 24,4 kg). The complete gun weighed 84,3 kg.
The 3,7cm Infanteriegeschutz M15 was derived from the 3,7cm Gebirgskanone (mountain gun) M13, also a light gun that could be transported disassembled. The concept of a demountable light infantry support guns was not restricted to Austria-Hungary; several countries designd, produced and used similar type guns. The 3,7cm infantery gun M15 was designed by Skoda in 1915 and tested by the Austrian army on the Italian front. In 1916 thousend 3,7cm Infantery guns M15 were produced and send to the front. The Italian army was quick to use captured guns against thier former owners and also started to produce the M15 themselves. Although the M15 was obsolete by the start of WW2, the guns were still in use in small numbers.
An interesting detail is the periscope type of sight on the gun that allows the gun to be fired from behind a cover.
Different types of ammunition were produced for the gun; A high explosive projectile with a base fuze, a signalling cartridge, a Shrapnel projectile containing 140 pcs 8mm hard lead balls, and the bounding high explosive shell as described below.
Despription and functioning of the shell:
The projectile consists of four main parts ; the steel shell body with two copper driving bands, the steel flange screwed in top of the shell body housing the pyrotechnic delay fuze and the detonator, the steel nosecap, and the hardened steel nose point housing the firing pin (green).
The brass shellcase is 57mm long and houses a linnen bag of powder.
In the shellbody three pellets of TNT (yellow) are stacked. Below the TNT pellets a pellet of smoke composition (brown) is placed. When the shell explodes a smoke plume will reveal the impact point of the shell.
In the steel flange above the explosive charge a brass tube housing the pyrotechnic delay composition is screwed. An aluminium flange is screwed in the lower side of this flange, the heat sensitive detonator is screwed into the aluminium flange.
The nosecap is pushed into the shell body with a tolerance fit, and glued into place with tar (as far as I can conclude from the black remains that dissolve in white spirit). A small screw in the side of the nosecap is used to fill the nosecap with the black powder bounding charge after the nosecap is ‘glued’ to the shell body. In top of the nosecap the fuze mechanim is placed, conisting of a firing cap housing with the firing cap (red), the sheet brass safety cylinder placed over the firing cap housing, and the brass inertia ring placed over the safety cylinder. A pressure spring is placed between the firing cap housing and the nose point. As long as the inertia ring is in forward position the firing cap cannot reach the firing pin (green).
When the shell is fired, inertia swings the inertia ring backward bending the lower flange of the safety cylinder along the firing cap housing. The inertia ring will now remain in the lower position. Upon impact the entire assembly (firig pin housing, safety ring and inertia ring) moves forward , riding the spring and pushing the firing cap (red) into the firing pin (green). The flame of the firing cap ignites the black powder bounding charge, igniting the pyrotechnic delay and bounding /propelling charge simultaniously, launching the shell body upward to approximately 1,5 to 2 metres before exploding mid air. This will enshure an optimal shrapnell effect. I suspect the grenade has about the yield of a handgrenade
Length of the complete cartridge : 185mm
Length of the projectile : 147mm
Length shellcase : 57mm
Maximum range : 2200 mtrs
Vo: 175 mtrs/sec
Regards, DJH
Therefore, a gun was designed that could fire a shell through the firing openings of the field fortifications from a relatively close range, but also was light enough to be carried over the battlefield disassembled in three pieces by three man (Barrel 34,6kg, carriage 25,3kg ; tripod 24,4 kg). The complete gun weighed 84,3 kg.
The 3,7cm Infanteriegeschutz M15 was derived from the 3,7cm Gebirgskanone (mountain gun) M13, also a light gun that could be transported disassembled. The concept of a demountable light infantry support guns was not restricted to Austria-Hungary; several countries designd, produced and used similar type guns. The 3,7cm infantery gun M15 was designed by Skoda in 1915 and tested by the Austrian army on the Italian front. In 1916 thousend 3,7cm Infantery guns M15 were produced and send to the front. The Italian army was quick to use captured guns against thier former owners and also started to produce the M15 themselves. Although the M15 was obsolete by the start of WW2, the guns were still in use in small numbers.
An interesting detail is the periscope type of sight on the gun that allows the gun to be fired from behind a cover.
Different types of ammunition were produced for the gun; A high explosive projectile with a base fuze, a signalling cartridge, a Shrapnel projectile containing 140 pcs 8mm hard lead balls, and the bounding high explosive shell as described below.
Despription and functioning of the shell:
The projectile consists of four main parts ; the steel shell body with two copper driving bands, the steel flange screwed in top of the shell body housing the pyrotechnic delay fuze and the detonator, the steel nosecap, and the hardened steel nose point housing the firing pin (green).
The brass shellcase is 57mm long and houses a linnen bag of powder.
In the shellbody three pellets of TNT (yellow) are stacked. Below the TNT pellets a pellet of smoke composition (brown) is placed. When the shell explodes a smoke plume will reveal the impact point of the shell.
In the steel flange above the explosive charge a brass tube housing the pyrotechnic delay composition is screwed. An aluminium flange is screwed in the lower side of this flange, the heat sensitive detonator is screwed into the aluminium flange.
The nosecap is pushed into the shell body with a tolerance fit, and glued into place with tar (as far as I can conclude from the black remains that dissolve in white spirit). A small screw in the side of the nosecap is used to fill the nosecap with the black powder bounding charge after the nosecap is ‘glued’ to the shell body. In top of the nosecap the fuze mechanim is placed, conisting of a firing cap housing with the firing cap (red), the sheet brass safety cylinder placed over the firing cap housing, and the brass inertia ring placed over the safety cylinder. A pressure spring is placed between the firing cap housing and the nose point. As long as the inertia ring is in forward position the firing cap cannot reach the firing pin (green).
When the shell is fired, inertia swings the inertia ring backward bending the lower flange of the safety cylinder along the firing cap housing. The inertia ring will now remain in the lower position. Upon impact the entire assembly (firig pin housing, safety ring and inertia ring) moves forward , riding the spring and pushing the firing cap (red) into the firing pin (green). The flame of the firing cap ignites the black powder bounding charge, igniting the pyrotechnic delay and bounding /propelling charge simultaniously, launching the shell body upward to approximately 1,5 to 2 metres before exploding mid air. This will enshure an optimal shrapnell effect. I suspect the grenade has about the yield of a handgrenade
Length of the complete cartridge : 185mm
Length of the projectile : 147mm
Length shellcase : 57mm
Maximum range : 2200 mtrs
Vo: 175 mtrs/sec
Regards, DJH
