For those not familiar with it, the M-79 is (was) a Vietnam Era grenade launcher which used a so-called "high-low pressure chamber" to hurl a 40mm grenade very accurately toward its target. Inside what looked like a very short and fat metallic shotshell case, the M-79 had a small chamber connected directly with the primer, which contained the propellant.

When the primer was activated, the propellant ignited, built up pressure, and ruptured the covering under a series of vents in the chamber, releasing the propellant gases into the much larger case and at the same time allowing the high pressure to subside (hence "high-low"). The relatively low pressure propelled the grenade down the rifled barrel, imparting a spin which armed the grenade after it had travelled far enough from the firer to be relatively harmless.

Unlike the WW II and Korean War "pineapple" grenade, the 40mm was smaller, lighter, ovoid and had a light metal casing. Inside the casing was an ovoid coil spring, conforming the the shape of the casing. The wire of this coil spring was notched at short intervals, causing it to fly apart in a vast number of tiny projectiles upon detonation of the explosive charge. The result was a cloud of tiny projectiles, fatal to those nearest the explosion, but harmless to those further away.

During my tour in Vietnam, we had one instance of a VC suspect being brought in with an unexploded M-79 grenade lodged in his back. The hospital team surrounded him with sandbags and gingerly removed the grenade, at great personal risk to the surgical staff.

Another VC suspect was found dead with an unexploded M-79 round planted squarely in his forehead.

Finally, one unfortunate gomer was standing in the chow line, with his loaded M-79 slung over his shoulder muzzle down. For some reason which has never been satisfactorily explained, the M-79 discharged accidentally, causing the grenade to burrow into the ground next to the foot of a gunnery sergeant, who happened also to be standing in line. Not for long.

The grenade did not explode. The gunnery sergeant did. The unfortunate Marine received an emphatic lesson in weapons handling on the spot, one which he was unlikely to forget.

To my knowledge, the M-79 has never been used as a hunting weapon.