It was designed to give downed aircrew a survival weapon for foraging wild game for food.

The M4 was developed from the Harrington & Richardson bolt-action M265 sporting rifle, adapted to a sheet metal frame with telescoping wire buttstock, a 14-inch detachable barrel chambered for .22 Hornet and the 4-shot detachable box magazine of the Savage Stevens M23D .22 Hornet sporting rifle.

The M4 weighs approximately four pounds and with barrel detached and telescoping stock closed makes a ~14-inch overall package.

[3] Due to the possible use of the M4 by downed aircrew as a combat weapon, the military-issue soft point ammunition in .22 Hornet carried a prohibition against this on the cartridge boxes: "Under no circumstances is the ammunition to be used for offensive or defensive measures against enemy personnel.

[4] It was later self-determined by the USAF that exigent circumstances and self-defense would have exempted soft point ammunition from that provision.