American Projectiles and Explosives
Resembling rockets in their shape because of the tube and stabilizing fin on their after end, rifle grenades are designed for about the same tactical purposes as are hand grenades. Rifle grenades have much greater range, however, and, because of their being launched at greater initial velocities, the forces of set-back and creep are employed in the design of their fuzes.
The launcher, on which the grenade is placed for firing, is an extension to the barrel of the rifle or carbine. A special device, integral with the launcher, attaches it securely to the muzzle of the weapon. US launchers are all of the spigot type; that is, the stabilizer assembly of the grenade fits over the launcher.
Classification of launchers
M1 - US rifles, caliber .30 M1903, M1903A, and M1903A3
M2 - US rifle, caliber .30 M1917
M7 - US rifle, caliber .30, M1, M1A3
The launcher M7 is secured to the Rifle M1 by a latch which clamps behind the bayonet lug. A valve screw, issued with the launcher, is substituted for the gas-cylinder lock screw. A stud on the launcher protrudes into the valve screw when the launcher is attached, opening the valve and providing for enough gas release to avoid damage to recoiling parts. The valve remains open as long as the launcher is attached to the rifle. The launcher has six gradations for different ranges. The range of the grenade is dependent upon the position of the stabilizer assembly on the launcher. A grenade-retainer spring, slightly larger in diameter than the launcher, holds the grenade at the position on the launcher for the selected range.
The Launcher M8 is similar to the Launcher M7, except that it is secured to the carbine by a simple clamp and wing nut.
If necessity demands, ball cartridges may be fired, even thought the launcher is attached, assuming, of course, that no grenade is on the launcher.
Rifle grenade cartridges
Rifle caliber, .30 M3: This cartridge is used in US rifle M1, M1903, M1903A1, M1903A3, and M1917. It is loaded in the standard caliber .30 case. The load consists of five grains of black powder and approximately 49 grains of a progressive-burning smokeless powder; the exact amount is adjusted to give the Anti-Tank Rifle Grenade M9A1 a velocity of 165 feet per second at five feet.
Carbine caliber, .30 M6: This cartridge is used in the US carbine M1, M1A1, and M1A3. It is loaded in the standard carbine cartridge case with approximately 21 grains of special powder adjusted to give the Anti-Tank Grenade M9A1 a velocity of 145 feet per second at 5 feet.
Auxiliary Grenade Cartridge M7: This cartridge, designed to give additional range when used in firing grenades from rifles and carbines, is a caliber .45 case drawn piece loaded with 20 grains of powder and sealed with a paper wad. It is placed in the end of a launcher, a rim on the base of the case holding the cartridge in place. It funcitons only in combination with the standard Grenade Cartridge M3 or M6 and fits the Launchers M1, M2, M7, and M8. When using this cartridge, the rifle or carbine will not be fired from the shoulder.
Next Time: Rifle Grenades (Part 2)