Ordnance Notes -- by Bob Stoner GMCM(SW) Ret.

Colt XM-148 40mm Grenade Launcher

A Colt XM-148 grenade launcher attached to a Colt XM-177E2 submachine gun. Note that the lower handguard is not used
when the launcher is attached to the barrel. The cumbersome sight for the launcher is just visible behind the launcher itself.

The Colt XM-148 was the first attempt to put a 40mm grenade launcher on the M-16 rifle. This experiment grew out of the Army's "wonder weapon" of the 1960's era: SPIW -- Special Purpose Individual Weapon. The SPIW was envisioned as a "point fire" weapon that shot bursts of 13-grain flechette projectiles or an "area fire" weapon that shot 40mm grenades -- ala the M-79.

The SPIW went through at least three generations before it became the SBR -- Serial Bullet Rifle -- and then faded away in the mid-1970s. However, the idea of a grenade launcher that attached to the infantry rifle caught on.
Colt's Firearms was the first out of the box with their XM-148 launcher. The barrel of the launcher telescoped forward from the receiver of the weapon to load. The barrel latch was a small pistol shaped grip that hinged forward to open the breech. There was a long combination trigger/safety rod attached to the receiver. The hook (trigger) attached to the end of the rod pivoted UP for SAFE and DOWN for FIRE. The triangular plastic handguards of the M-16 were replaced by a sheet metal stamping and a dial sight (similar to an enlarged version of rifle grenade sight) attached to the left side of the launcher for direct or indirect fire. Several hundred XM-148 launchers ere manufactured and evaluated from 1965 to 1967 when it was rejected for the XM-203 launcher. The photo shows an XM-148 launcher attached to the M-177E2 5.56mm submachinegun (aka CAR-15). Most SEAL grenadiers were still sing the XM-148 launcher at SEA FLOAT/SOLID ANCHOR. MST-2 units preferred the M-79.



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2002 Bob Stoner