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The Firefly was an American submachine gun produced by the Armament Technology Corporation.


The Firefly was designed in 1970 by Robert Irwin. Initial prototypes were built from converted Wilkinson carbines. In 1974, the design was picked up by the Armament Technology Corporation and was produced in small numbers as a semi-automatic carbine for the civilian market. A fully-automatic model was developed in 1977, and negotiations were underway with a third party to put the gun into full production, but ultimately these plans fell through and only five prototypes of the submachine gun were made.


The Firefly operated on a delayed blowback principle using a gas retardant system. The weapon fired from a closed bolt with a loose hammer. Upon firing, the excess gas pressure exerted from the discharge would escape through a gas port opening on the inside of the barrel. The port would lead this gas backward into an isolated chamber connected to a plate, which in turn was connected to the bolt. The gas pressure would push against the plate and cause some resistance to the bolt's rearward movement, resulting in a controllable bolt delay.

The semi-automatic firemode of the Firefly disconnected the sear from the trigger entirely, and as a result the hammer was unable to move unless the trigger was pulled again.

The first prototypes of the Firefly fed from Sten magazines, but production models used Smith & Wesson Model 59 magazines. The cocking slot was located along the top of the receiver.



  • Two prototypes were known to have been owned by American adult film actors Marilyn Chambers and her ex-husband Chuck Traynor.[1]