Back (Rifle Grenades)

 M1, M2, M7 and M8 Launchers and Accessories

When the U.S. entered World War Two the bolt action Model 1903 Springfield was the principal service rifle in use, with the M1917 Enfield as limited standard. It would be a couple of years before quantities of the new M1 Garand would be available.
A specific grenade launcher adapter would be necessary for each rifle.

Spigot Types M1 & M2
The M1 and M2 were simple clamp-on tubular extensions. These had oversized smooth bores which did not interfere with the rifle's operation.
The bands on the launching tube were used to help adjust range. The greater the number of rings left exposed below the bottom of the grenade, the less distance it would travel.

The M1 & M2 were essentially unmodified for their entire service life. They were declared obsolete, along with the rifles at the end of WWII.

Spigot Types M7 & M8
Adapting the Garand rifle was a bit more complicated.
When operating normally, a small amount of gas pressure from the fired cartridge is directed down into the gas cylinder below the muzzle. That pressure provides the energy which cycles the bolt, chambering the next round. Unfortunately, when the bolt opens, barrel pressure is released which is needed to propel a rifle grenade.
It took a bit of effort and time to come up with an appropriate solution.

When mounted (using the bayonet lug for an attachment point), the M7 launcher opens a small vent in the gas cylinder end plug, providing a pressure release which prevents the bolt from cycling. This maximizes the gas propellant out the muzzle enabling a grenade to be launched.  The down side of this design was the launcher had to be removed to restore semi-automatic function.
To reslove this shortcoming  a modified launcher, the  M7A1, incorporated a spring loaded mounting latch which would only open the gas plug vent when a grenade was fired. The improvement was too late to see use in WWII.

Problems didn't stop there however. The M7A1 was recoil operated which put stress on other muzzle parts, so it had to be redesigned again (M7A2). During the Korean conflict, grenade sizes were in increased, and so was the launcher's length, to provide optimal performance. The final variant for the Garand rifle, was the M7A3.   Detail;

Today, grenade launcher capability is now commonly incorporated into the muzzle design of modern combat rifles, thereby eliminating the need to add anything extra.

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