The M7 grenade launcher was a tube-shaped device with an overall length (including the mounting bracket) of 7.5 inches.
One end fitted onto the barrel of the M1 Garand rifle enclosing the muzzle, and was held in place with the rifle's bayonet lug.
The other end was cylindrical with a small clip that held the grenade in place by friction.
To launch a grenade, a special high-powered blank cartridge made specifically for the purpose (the .30-06 Springfield M3 grenade cartridge) was chambered in the rifle.
Using markings engraved onto the device to determine the desired range, the rifle grenade was slipped over the launcher.
When fired, the resulting expanding gases propelled the grenade a considerable distance depending on the grenade type, the vertical angle that the rifle was held, and how far the grenade was positioned onto the launcher.
Since the device disabled the semi-automatic function of the rifle to prevent damage to the gun from firing grenades, the rifle could not be fired normally when the M7 launcher was in place; the gun could be fired in an emergency by cycling the action by hand.
Fragmentation, anti-tank, and smoke grenades and pyrotechnic signals were available along with an adapter to enable the use of hand grenades.
One to three M7 grenade launchers were issued to each rifle squad depending on period.
It was also issued to support and headquarters elements.

The M7 series grenade launcher came with accessories.
The M15 auxiliary sight was mounted on the left-hand side of the stock accompanied by a template to allow it to be properly positioned on the stock.
A spirit level allowed the user to figure out the arc of the weapon to aid in aiming the grenade.
A rubber recoil boot (part No.
B200968) could be slipped on the butt of the Garand's stock to reduce recoil when it was fired.

The M7 Auxiliary Grenade Cartridge booster charge, or "Vitamin Pill", could be inserted into the M7 grenade launcher's muzzle to increase its range by an additional 100 to 150 yards.
These booster charges were made from cut-down .45 Long Colt revolver cartridges, with a small hole in the base and  a red cardboard disc inside the case over the charge.
The charge was loaded into the launcher's muzzle like a shotgun shell (with the rim keeping it in place) and the rifle grenade was slid into place over it.
When the blank cartridge was fired, its flame would travel up the rifle's barrel, ignite the booster charge, and propel the booster cartridge into the base of the rifle grenade.
The booster cartridge would fall out of the rifle grenades tail fin assembly in flight.

The M8 grenade launcher was similar except it was designed to be mounted on the M1 carbine and used the .30 Carbine M6 grenade cartridge.
Users of the M8 needed to be careful to fire it with the M1 Carbine's stock braced sideways, as the recoil could crack or break the stock.
The M7 grenade launcher was a tube-shaped device with an overall length (including the mounting bracket) of 7.5 inches. One end fitted onto the barrel of the M1 Garand rifle enclosing the muzzle, and was held in place with the rifle's bayonet lug. The other end was cylindrical with a small clip that held the grenade in place by friction. To launch a grenade, a special high-powered blank cartridge made specifically for the purpose (the .30-06 Springfield M3 grenade cartridge) was chambered in the rifle. Using markings engraved onto the device to determine the desired range, the rifle grenade was slipped over the launcher. When fired, the resulting expanding gases propelled the grenade a considerable distance depending on the grenade type, the vertical angle that the rifle was held, and how far the grenade was positioned onto the launcher. Since the device disabled the semi-automatic function of the rifle to prevent damage to the gun from firing grenades, the rifle could not be fired normally when the M7 launcher was in place; the gun could be fired in an emergency by cycling the action by hand. Fragmentation, anti-tank, and smoke grenades and pyrotechnic signals were available along with an adapter to enable the use of hand grenades. One to three M7 grenade launchers were issued to each rifle squad depending on period. It was also issued to support and headquarters elements.
The M7 series grenade launcher came with accessories. The M15 auxiliary sight was mounted on the left-hand side of the stock accompanied by a template to allow it to be properly positioned on the stock. A spirit level allowed the user to figure out the arc of the weapon to aid in aiming the grenade. A rubber recoil boot (part No. B200968) could be slipped on the butt of the Garand's stock to reduce recoil when it was fired.
The M7 Auxiliary Grenade Cartridge booster charge, or "Vitamin Pill", could be inserted into the M7 grenade launcher's muzzle to increase its range by an additional 100 to 150 yards. These booster charges were made from cut-down .45 Long Colt revolver cartridges, with a small hole in the base and  a red cardboard disc inside the case over the charge. The charge was loaded into the launcher's muzzle like a shotgun shell (with the rim keeping it in place) and the rifle grenade was slid into place over it. When the blank cartridge was fired, its flame would travel up the rifle's barrel, ignite the booster charge, and propel the booster cartridge into the base of the rifle grenade. The booster cartridge would fall out of the rifle grenades tail fin assembly in flight.
The M8 grenade launcher was similar except it was designed to be mounted on the M1 carbine and used the .30 Carbine M6 grenade cartridge. Users of the M8 needed to be careful to fire it with the M1 Carbine's stock braced sideways, as the recoil could crack or break the stock.
M7 grenade launcher