Cutaway model of a “7,5 patroon brisantgranaatkartets met tijd-schokbuis No.12” / “Cartridge high explosive shrapnell with a time-impact fuze No.12, as used in the “Gun 7 field “ (Kanon 7 veld) with the Dutch artillery prior to WW2. In 1904 the gun was taken into service with the Dutch army, it had a max. Range of 6.500 mtrs. In 1926 the gun was modernised, which resulted in a max. range of 10.000 mtrs. With the mobilistaion in 1939 the Dutch army had 280 pcs. of 7 veld available for use.
The projectile body is made of steel. In top of the body the bgtk (Brisantgranaatkop / high explosive head part) is pressed held in place with dowel pins. The bgtk part serves as the lock up cap for the schrappnell balls charge, a centering device for the flamepipe and a well to receive the time-impact fuze No.12. The fuze is not screwed, but placed in the bgtk head part and locked in place with a pointed radial screw. The lower end of the flame pipe is centered by the expulsion flange. Below the expulsion flange a expulsion charge, existing of 70 grams black powder is placed. The flame pipe is filled with a pipe made of black powder- that boosts the flame of the time-impact fuze No.12 when travelling down. The filler charge of the projectile exists of lead balls. The lower 1/3 part of the balls is cast in inert resign (white), the middle 1/3 part of the lead balls is cast in sulfer (brown), the upper 1/3 part of the lead balls is cast in 75 grams of trotyl (TNT).
The bgtk (brisantgranaatkop) has a charge of 92 grams trotyl with a smoke pellet in the middle. The smoke pellet is used to observe the point of impact.
The brisantgranaatkartets can function in two ways:
1- As a shrappnel projectile: before firing the projectile, the fuze is set on the desired fuze activation distance after which the projectile is fired. At appr. 150 mtrs. before the target, the fuze is activated. The flame of the fuze travels down the pipe into the expulsion charge which ignites. The expulsion flange is now pushed upward up to the moment where the dowel pins break and the bgtk is thrown off forward and the charge of lead balls is projected forward (in airburst), the projectile body serving as a kind of barrel. The rotation of the projectiel enshures the balls are thrown outward so a conical shaped pattern of dispersion of balls appears. The resign, sulfer and trotyl are blown away as dust. The loose bgtk part will continue it’s path and explode on impact with the ground.
2- As a high explosive projectile: The time function of the fuze is shutt off by rotating the + mark on the lower pyrotechnic ring over the zero line on the body, leavuing only the impact function of the fuze. Upon impact the lower firing cap moves forward into the firing pin, igniting the radial placed detonator No.5 (white) in the lower part of the fuze body. This will ignite the main charge of 92 grams Trotyl in the bgtk and the 75 grams cast between the balls below it. This is enough to make the projectile function like a high explosive shell.
The shrappnel projectile is meant primarally against groups of –dug in and non dug in- troops as well as unarmoured targets.
Functioning of time impact fuze No.12:
The fuze has two inertia activated firing cap assembly’s. The upper firing cap assembly is held in place by a cap with two outward bend lips that hook behind two slots in the fuze body. A brass shear wire further fixates the firing cap assembly. Upon firing, the firing cap assembly moves backward due to inertia bending the lips inward and breaking the shear wire. The firing cap moves into the firing pin below it and ignites the pyrotechnic powder delay train in the upper and lower rings. The distance is set by rotating the lower ring by means of a key. The division is in mtrs. ranging from 0-5600 mtrs with 50 mtrs. divisions.
The groove in the lower ring –housing the black powder train- is interrupted for about one cm. Rotating this part above the flash hole of the magazine shuts off the time function, leaving the impact function only. This position can be recognized by the + on the outside of the lower ring being set above the zero set line on the outer rim of the body. Rotating the lower ring into the 5600 mtrs. direction ring will lengthen the path of black powder to be burned. The upper ring is fixed by means of two pins and cannot rotate. It has a flash-through hole that passes the flame of the upper firing cap directly into the lower ring. If the black powder in the lower ring is burned up the flame will travel into the flame pipe of the expulsion charge. This will activate the shrappnell function of the projectile.
The lower firing cap assembly ( impact fuze function) is held away from the firing pin –on a bridge piece above it- by a small black powder safety pellet pressed in a space below the upper firing pin. Upon firing on impact mode, the upper firing cap ignites the black powder safety pellet through four small holes around the upoper firing pin. After the pellet has burned away, -upon impact- the firing cap assembly can move forward ,-riding the creep spring- pressing the firing cap into the firing pin. The flame will ignite detonator No.12 (white)
The setting shown in this cutaway is 0 mtrs, this however is the best setting to explain the functioning of the fuze.
The shellcase used is the “ Kardoes Mg. Van 7 veld” shellcase Brass Gun 7 field. The main charge exists of “RB vlamvrij pijpen 206x6/5” Smokeless and Flameless sticks 206mm long , 6 mm outer diameter with a 5 mm diameter hole. In the base of the shellcase a percussion primer No.2 is screwed. In contrast to the HE projectile that has a seperate charge, the shrappnel projectile is a fixed cartridge. On top of the powder charge a cartboard closure cap is placed.
Length of the shellcase: 277 mm
Length of projectile: 266 mm
Length of complete cartridge: 509 mm
The projectile is an original factory cutaway model in reasonable condition, so it was to just patch it up where neccecerry
Regards DJH
The projectile body is made of steel. In top of the body the bgtk (Brisantgranaatkop / high explosive head part) is pressed held in place with dowel pins. The bgtk part serves as the lock up cap for the schrappnell balls charge, a centering device for the flamepipe and a well to receive the time-impact fuze No.12. The fuze is not screwed, but placed in the bgtk head part and locked in place with a pointed radial screw. The lower end of the flame pipe is centered by the expulsion flange. Below the expulsion flange a expulsion charge, existing of 70 grams black powder is placed. The flame pipe is filled with a pipe made of black powder- that boosts the flame of the time-impact fuze No.12 when travelling down. The filler charge of the projectile exists of lead balls. The lower 1/3 part of the balls is cast in inert resign (white), the middle 1/3 part of the lead balls is cast in sulfer (brown), the upper 1/3 part of the lead balls is cast in 75 grams of trotyl (TNT).
The bgtk (brisantgranaatkop) has a charge of 92 grams trotyl with a smoke pellet in the middle. The smoke pellet is used to observe the point of impact.
The brisantgranaatkartets can function in two ways:
1- As a shrappnel projectile: before firing the projectile, the fuze is set on the desired fuze activation distance after which the projectile is fired. At appr. 150 mtrs. before the target, the fuze is activated. The flame of the fuze travels down the pipe into the expulsion charge which ignites. The expulsion flange is now pushed upward up to the moment where the dowel pins break and the bgtk is thrown off forward and the charge of lead balls is projected forward (in airburst), the projectile body serving as a kind of barrel. The rotation of the projectiel enshures the balls are thrown outward so a conical shaped pattern of dispersion of balls appears. The resign, sulfer and trotyl are blown away as dust. The loose bgtk part will continue it’s path and explode on impact with the ground.
2- As a high explosive projectile: The time function of the fuze is shutt off by rotating the + mark on the lower pyrotechnic ring over the zero line on the body, leavuing only the impact function of the fuze. Upon impact the lower firing cap moves forward into the firing pin, igniting the radial placed detonator No.5 (white) in the lower part of the fuze body. This will ignite the main charge of 92 grams Trotyl in the bgtk and the 75 grams cast between the balls below it. This is enough to make the projectile function like a high explosive shell.
The shrappnel projectile is meant primarally against groups of –dug in and non dug in- troops as well as unarmoured targets.
Functioning of time impact fuze No.12:
The fuze has two inertia activated firing cap assembly’s. The upper firing cap assembly is held in place by a cap with two outward bend lips that hook behind two slots in the fuze body. A brass shear wire further fixates the firing cap assembly. Upon firing, the firing cap assembly moves backward due to inertia bending the lips inward and breaking the shear wire. The firing cap moves into the firing pin below it and ignites the pyrotechnic powder delay train in the upper and lower rings. The distance is set by rotating the lower ring by means of a key. The division is in mtrs. ranging from 0-5600 mtrs with 50 mtrs. divisions.
The groove in the lower ring –housing the black powder train- is interrupted for about one cm. Rotating this part above the flash hole of the magazine shuts off the time function, leaving the impact function only. This position can be recognized by the + on the outside of the lower ring being set above the zero set line on the outer rim of the body. Rotating the lower ring into the 5600 mtrs. direction ring will lengthen the path of black powder to be burned. The upper ring is fixed by means of two pins and cannot rotate. It has a flash-through hole that passes the flame of the upper firing cap directly into the lower ring. If the black powder in the lower ring is burned up the flame will travel into the flame pipe of the expulsion charge. This will activate the shrappnell function of the projectile.
The lower firing cap assembly ( impact fuze function) is held away from the firing pin –on a bridge piece above it- by a small black powder safety pellet pressed in a space below the upper firing pin. Upon firing on impact mode, the upper firing cap ignites the black powder safety pellet through four small holes around the upoper firing pin. After the pellet has burned away, -upon impact- the firing cap assembly can move forward ,-riding the creep spring- pressing the firing cap into the firing pin. The flame will ignite detonator No.12 (white)
The setting shown in this cutaway is 0 mtrs, this however is the best setting to explain the functioning of the fuze.
The shellcase used is the “ Kardoes Mg. Van 7 veld” shellcase Brass Gun 7 field. The main charge exists of “RB vlamvrij pijpen 206x6/5” Smokeless and Flameless sticks 206mm long , 6 mm outer diameter with a 5 mm diameter hole. In the base of the shellcase a percussion primer No.2 is screwed. In contrast to the HE projectile that has a seperate charge, the shrappnel projectile is a fixed cartridge. On top of the powder charge a cartboard closure cap is placed.
Length of the shellcase: 277 mm
Length of projectile: 266 mm
Length of complete cartridge: 509 mm
The projectile is an original factory cutaway model in reasonable condition, so it was to just patch it up where neccecerry
Regards DJH
