Caseless (literally) 40mm Grenade

The “RIFLE-GAS LAUNCHED GRENADE CONCEPT” is a 1973 report from Rock Island Arsenal ( ) that describes a feasibility study on a “novel” approach for launching a 40mm grenade.

This “novel” approach consisted of using propellant gases from a fired rifle ball cartridge (tapping off propellant gases) to launch a 40mm grenade (in a separate under barrel tube) eliminating the need for a grenade cartridge case. The test bed was a M16A1 rifle with special under barrel 40mm grenade launch barrel (shown below).

40mm XM387 inert test grenade projectiles used in the test.

Does anyone have or has anyone seen one of these stand alone 40mm XM387 inert grenade projectiles? Better picture?
Was the XM387 projectile “borrowed” from a 40mm cartridge (projectile & case) or was the XM387 projectile a stand alone experimental item?


Interesting, not heard of that one.

The Russians did something similar with a couple of special forces 30mm grenades launched by blanks. They used different versions of “sealed piston” technology which trapped the propellant gases so were virtually silent.

Brian, this one is less “caseless” than just a normal rifle grenade system where the launcher cup was just moved under the barrel.