Cutaway model of a the 7,5cm SprGr. (Dopp.Z) 260-2 (j) for the 75mm Skoda M1928 mountain gun.
The Guns and projectiles are Skoda produced for the pre WW2 Yugoslav and Albanian army and captured guns were used by the Croatian NDH fraction and the German army during WW2. In German use the gun was called the ‘7.5cm Geb.K 285 (j)’.
The projectile is made of forged and machined steel. A brass bushing is placed around the detonator of the fuze, protecting the explosive charge in the projectile body.
The fuze used on the shell is the Skoda manufactured time –impact fuze MG-CR. The Time fuze is a pyrotechnic fuze using a rotation ring to set the desired time . It is activated by a set back mechanism (pict 04) where a firing cap is driven into a firing pin by set back upon firing, igniting the pyrotechnic train. The green painted holes (pict 03 & 04) allow for the burnt powder gasses to escape. When burned up, the black powder magazine in the base of the fuze ignites the detonator in the base of the fuze body.
The impact fuze is placed in top of the fuze(pict 03). Upon firing, the light blue lock up bushing moves down due to inertia , allowing both balls that lock the firing pin in forward position to move outward, climbing the upward chamfered holes when acceleration is nullified (Velocity is constant). Upon impact, the firing pin is hammered down into the firing cap (red) , launching a flame down through the dark blue channel into the detonator in the base of the fuze body.
The booster assembly screwed to the base of the fuze body has an interesting safety mechanism. A rotor with a hole is placed in the booster, the hole 90 degrees out of line. The rotor is fixated in this position by a spring loaded bushing (blue) and a small steel ball, preventing the bushing from further movement upward. Upon firing, inertia pulls the bushing downward , riding the spring, until acceleration is nullified and the bushing moves forward again. The steel ball is thrown outward by centrifugal force, allowing the bushing to move upward further, rotating the rotor by means of a projection attached to the rotor from off line to in line. Only activation of this mechanism arms the fuze.
The 173mm long shell case is brass made and has a four piece charge. Depending upon the desired range bag 2, 3, and 4 can be taken away.
Length of The projectile : 361mm
Weight of the projectile : 6,3 kg
Rate of fire : 4 Rpm
Vo: 425 mtrs/sec (1394 ft/sec)
Max. range : 8.700 mtrs (9.500 Yards)
A big thank you to Erik (BLU-97) who finally found the needed info about the powder charges in the shell case.
Regards, DJH.
The Guns and projectiles are Skoda produced for the pre WW2 Yugoslav and Albanian army and captured guns were used by the Croatian NDH fraction and the German army during WW2. In German use the gun was called the ‘7.5cm Geb.K 285 (j)’.
The projectile is made of forged and machined steel. A brass bushing is placed around the detonator of the fuze, protecting the explosive charge in the projectile body.
The fuze used on the shell is the Skoda manufactured time –impact fuze MG-CR. The Time fuze is a pyrotechnic fuze using a rotation ring to set the desired time . It is activated by a set back mechanism (pict 04) where a firing cap is driven into a firing pin by set back upon firing, igniting the pyrotechnic train. The green painted holes (pict 03 & 04) allow for the burnt powder gasses to escape. When burned up, the black powder magazine in the base of the fuze ignites the detonator in the base of the fuze body.
The impact fuze is placed in top of the fuze(pict 03). Upon firing, the light blue lock up bushing moves down due to inertia , allowing both balls that lock the firing pin in forward position to move outward, climbing the upward chamfered holes when acceleration is nullified (Velocity is constant). Upon impact, the firing pin is hammered down into the firing cap (red) , launching a flame down through the dark blue channel into the detonator in the base of the fuze body.
The booster assembly screwed to the base of the fuze body has an interesting safety mechanism. A rotor with a hole is placed in the booster, the hole 90 degrees out of line. The rotor is fixated in this position by a spring loaded bushing (blue) and a small steel ball, preventing the bushing from further movement upward. Upon firing, inertia pulls the bushing downward , riding the spring, until acceleration is nullified and the bushing moves forward again. The steel ball is thrown outward by centrifugal force, allowing the bushing to move upward further, rotating the rotor by means of a projection attached to the rotor from off line to in line. Only activation of this mechanism arms the fuze.
The 173mm long shell case is brass made and has a four piece charge. Depending upon the desired range bag 2, 3, and 4 can be taken away.
Length of The projectile : 361mm
Weight of the projectile : 6,3 kg
Rate of fire : 4 Rpm
Vo: 425 mtrs/sec (1394 ft/sec)
Max. range : 8.700 mtrs (9.500 Yards)
A big thank you to Erik (BLU-97) who finally found the needed info about the powder charges in the shell case.
Regards, DJH.
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