pzgr40
Well-Known Member
Cutaway model of a 175mm M437A1 HE projectile as used in the M-107 Self Propelled gun. The projectile uses fragmentation, blast and mining to destroy a target. Targets are to be considered anything within range. Maximum range of the projectile is 32.800 mtrs. Vo. is 914 mtrs/sec when using the maximum powder charge.
The projectile consists of a hollow steel forging with a boat tailed base, and a streamlined ogive. A wide red copper driving band is placed on the just above the boat tailed base. Below the red copper driving band a white nylon obturation ring is placed in a groove to ensure a gas tight seal.
At the base, a 1,5 mm thick disc is welded that forms an extra seal. When the projectile is forged small cracks can appear in the base, so the disc prevents hot gas from reaching the explosive charge and cause a premature explosion.
The explosive charge is cast. The projectile has a deep fuze cavity that is normally filled with a 0,30Lb TNT supplementary charge packed in an aluminium container. When using a fuze with a long tail piece, the supplementary charge is removed. Depending on the fuze used, the projectile explodes on impact (M-572 series impact fuze), after digging in upon impact (M-572 with delay setting), or in airburst mode when using the VT M514 series (proximity) fuze .
When firing the projectile with the maximum charge, the acceleration force was so tremendous that the normal M557 PD fuzes hollow nose piece buckled. Therefore, the M557 PD was modified by filling the hollow nose cap with polyester resign, and so reinforce the nose cap. This fuze was renamed M-572 PD and is used only for the 175mm M437 projectile.
As it is difficult to make large projectiles of the exactly the same weight, each projectile is classed in one of four weight zones :
Zone I : over 142,75Lb. (64,75 kg)and up to & incl. 143,96Lb.
Zone II : over 143,84 Lb and up to & incl. 145,05Lb.
Zone III : over 144,93 Lb and up to & incl. 146,14Lb.
Zone IV : over 146,02 Lb and up to & incl. 147,23 Lb (66,78 kg).
The weight zone of the projectile is indicated by the number of prick punch marks on the ogive of the projectile.
The weight of the projectile is taken into consideration when calculating the flight trajectory.
There are two types of 175mm M437 projectiles available:
the M437A1 model which is filled with 30Lb (13,6 kg)TNT,
the M437A2 model which is filled with 31Lb (14 kg) Comp. B. Both use a 0,30Lb (0,136 kg) Supplementary TNT charge below the fuze.
The 175mm M-107 Self Propelled gun uses the same chassis and gun carriage as the M110 8 (203mm) Gun. As the M-107 S.P. gun only weighs 28.200 Kg it is air transportable.
The M-107 self-propelled gun was used by the following countries:
Greece, Iran, Israel, Italy, Netherlands, South Korea, Spain, Turkey, United states of America, United Kingdom and Germany.
Due to its great range the M-107 had an outstanding reputation and saw extensive action in the Vietnam war, the 1973 Yom Kippoer war and the Iran-Iraq war.
One deadly problem occurred when using the gun in the 70s of the last century. Due to the large and long- explosive cavity, the cast in explosive charge (cast in at 81,5 degrees celcius) started giving off vapours and trapped air that was pushed downward while the explosive charge solidified, leaving a 0,030 (0,76mm) gap at the base of the explosive charge. Upon firing of the projectile the explosive charge slammed down into the base of the cavity, causing the projectile to explode in the barrel, a so called premature. This problem was solved by adjusting the casting process, and NDT testing each separate manufactured projectile by means of X-ray inspection;
A report describing the problem and the solution by X-raying the projectile can be found here:
http://www.google.nl/url?sa=t&rct=j...=vALaHJNjborZIZhB-il-Nw&bvm=bv.69411363,d.ZWU
Another problem was that the pressure in the barrel rose to 45.700Psi (3.150 Bar) when firing with the full powder charge. Small cracks and granular inclusions, caused by the production process of the relatively long barrel resulted in barrels that exploded. The pressure will not be a problem when one fires powder charges for a shorter range with a lower pressure (charge1 or 1&2). However, firing at full range (charges 1, 2 & 3), barrel life was reduced to 300 shots. Later barrels were made with an improved production process had a 1200 shots barrel life.
http://www.google.nl/url?sa=t&rct=j...OzWxa6pdct1frgdCg&sig2=p8Fz9qcIvR_J_zn4SufN8w
An instruction movie showing the M-107 firing can be found here :
https://www.youtube.com/watch?v=WhfgdsawrzM
https://www.youtube.com/watch?v=ZmHNqeEASmk
A site dedicated to the M-107 in Dutch service;
http://www.107afdva.nl/index.htm
Projectiles were also manufactured in the Netherlands by the AI (Artillerie Inrichtingen) in Zaandam. The factory closed due to lack of ammo requirements at the end of the cold war.
Regards, DJH
The projectile consists of a hollow steel forging with a boat tailed base, and a streamlined ogive. A wide red copper driving band is placed on the just above the boat tailed base. Below the red copper driving band a white nylon obturation ring is placed in a groove to ensure a gas tight seal.
At the base, a 1,5 mm thick disc is welded that forms an extra seal. When the projectile is forged small cracks can appear in the base, so the disc prevents hot gas from reaching the explosive charge and cause a premature explosion.
The explosive charge is cast. The projectile has a deep fuze cavity that is normally filled with a 0,30Lb TNT supplementary charge packed in an aluminium container. When using a fuze with a long tail piece, the supplementary charge is removed. Depending on the fuze used, the projectile explodes on impact (M-572 series impact fuze), after digging in upon impact (M-572 with delay setting), or in airburst mode when using the VT M514 series (proximity) fuze .
When firing the projectile with the maximum charge, the acceleration force was so tremendous that the normal M557 PD fuzes hollow nose piece buckled. Therefore, the M557 PD was modified by filling the hollow nose cap with polyester resign, and so reinforce the nose cap. This fuze was renamed M-572 PD and is used only for the 175mm M437 projectile.
As it is difficult to make large projectiles of the exactly the same weight, each projectile is classed in one of four weight zones :
Zone I : over 142,75Lb. (64,75 kg)and up to & incl. 143,96Lb.
Zone II : over 143,84 Lb and up to & incl. 145,05Lb.
Zone III : over 144,93 Lb and up to & incl. 146,14Lb.
Zone IV : over 146,02 Lb and up to & incl. 147,23 Lb (66,78 kg).
The weight zone of the projectile is indicated by the number of prick punch marks on the ogive of the projectile.
The weight of the projectile is taken into consideration when calculating the flight trajectory.
There are two types of 175mm M437 projectiles available:
the M437A1 model which is filled with 30Lb (13,6 kg)TNT,
the M437A2 model which is filled with 31Lb (14 kg) Comp. B. Both use a 0,30Lb (0,136 kg) Supplementary TNT charge below the fuze.
The 175mm M-107 Self Propelled gun uses the same chassis and gun carriage as the M110 8 (203mm) Gun. As the M-107 S.P. gun only weighs 28.200 Kg it is air transportable.
The M-107 self-propelled gun was used by the following countries:
Greece, Iran, Israel, Italy, Netherlands, South Korea, Spain, Turkey, United states of America, United Kingdom and Germany.
Due to its great range the M-107 had an outstanding reputation and saw extensive action in the Vietnam war, the 1973 Yom Kippoer war and the Iran-Iraq war.
One deadly problem occurred when using the gun in the 70s of the last century. Due to the large and long- explosive cavity, the cast in explosive charge (cast in at 81,5 degrees celcius) started giving off vapours and trapped air that was pushed downward while the explosive charge solidified, leaving a 0,030 (0,76mm) gap at the base of the explosive charge. Upon firing of the projectile the explosive charge slammed down into the base of the cavity, causing the projectile to explode in the barrel, a so called premature. This problem was solved by adjusting the casting process, and NDT testing each separate manufactured projectile by means of X-ray inspection;
A report describing the problem and the solution by X-raying the projectile can be found here:
http://www.google.nl/url?sa=t&rct=j...=vALaHJNjborZIZhB-il-Nw&bvm=bv.69411363,d.ZWU
Another problem was that the pressure in the barrel rose to 45.700Psi (3.150 Bar) when firing with the full powder charge. Small cracks and granular inclusions, caused by the production process of the relatively long barrel resulted in barrels that exploded. The pressure will not be a problem when one fires powder charges for a shorter range with a lower pressure (charge1 or 1&2). However, firing at full range (charges 1, 2 & 3), barrel life was reduced to 300 shots. Later barrels were made with an improved production process had a 1200 shots barrel life.
http://www.google.nl/url?sa=t&rct=j...OzWxa6pdct1frgdCg&sig2=p8Fz9qcIvR_J_zn4SufN8w
An instruction movie showing the M-107 firing can be found here :
https://www.youtube.com/watch?v=WhfgdsawrzM
https://www.youtube.com/watch?v=ZmHNqeEASmk
A site dedicated to the M-107 in Dutch service;
http://www.107afdva.nl/index.htm
Projectiles were also manufactured in the Netherlands by the AI (Artillerie Inrichtingen) in Zaandam. The factory closed due to lack of ammo requirements at the end of the cold war.
Regards, DJH
, it woud be a valuable addition to my submunition shells collection.
