Cutaway model of a 75mm M309A1 High Explosive shell for the M20 recoilless rifle. This Rifle was placed on the M1917A1 tripod, which was originally meant for the browning machine gun. The weapon was used in the last days of WW2 and was exstensively used in the Korean war, where it was used against field fortifications and pillboxes.
After the Korean war the recoiless rifle was replaced by guided missiles, which were more accurate and lighter.
Today the M20 recoiless rifle is used only by the US national forrest service as an anti avalanche system.
The working principal of the M18 Recoilless rifle can simply be described as “weight of gas from breech X speed of gas = weight of projectile X speed of projectile”. As long as this is in balance, the weapon is recoilless.
The shell case is perforated with 922 holes to let the gas vent afterward through the perforated breech block, the driving band of the projectile is pre-engraved as to lose no energy to rifling of the driving belt. Another reason for using pre-engraved driving belts is to prevent the pressure in the chamber from rising too high, as the recoilless rifle is also quite a thin walled light weapon . The absence of a recoil system also greatly reduces the weight of the weapon.
The projectile is filled with 0,675 kg of TNT
The shellcase is filled with 1,5 kg of smokeless powder
Weight of the complete cartridge is 10,2 kg
Weight of the projectile with fuze is 6,5 kg
Length of the complete cartridge is 73,5cm
Length of the cartridge case is 40,5cm
Length of the projectile with fuze is 38,5cm
Vo is 300 mtrs/sec
Maximum range is 6350 mtrs
Threre are four types of shells available :
-the M309A1 High explosive
-the M310A1 HEAT shell
-the M311A1 Smoke (Phospor)
-the Drill cartridge M38
Regards, DJH
After the Korean war the recoiless rifle was replaced by guided missiles, which were more accurate and lighter.
Today the M20 recoiless rifle is used only by the US national forrest service as an anti avalanche system.
The working principal of the M18 Recoilless rifle can simply be described as “weight of gas from breech X speed of gas = weight of projectile X speed of projectile”. As long as this is in balance, the weapon is recoilless.
The shell case is perforated with 922 holes to let the gas vent afterward through the perforated breech block, the driving band of the projectile is pre-engraved as to lose no energy to rifling of the driving belt. Another reason for using pre-engraved driving belts is to prevent the pressure in the chamber from rising too high, as the recoilless rifle is also quite a thin walled light weapon . The absence of a recoil system also greatly reduces the weight of the weapon.
The projectile is filled with 0,675 kg of TNT
The shellcase is filled with 1,5 kg of smokeless powder
Weight of the complete cartridge is 10,2 kg
Weight of the projectile with fuze is 6,5 kg
Length of the complete cartridge is 73,5cm
Length of the cartridge case is 40,5cm
Length of the projectile with fuze is 38,5cm
Vo is 300 mtrs/sec
Maximum range is 6350 mtrs
Threre are four types of shells available :
-the M309A1 High explosive
-the M310A1 HEAT shell
-the M311A1 Smoke (Phospor)
-the Drill cartridge M38
Regards, DJH
