The Avenger is a homemade SMG of Northern Irish origin attributed to Ulster loyalist paramilitary groups. It was made during the 90s in a private machine shop somewhere near Belfast.
Ulster loyalist paramilitary groups had made many different home-made submachine guns over the course of The Troubles. The Avenger is one of the more notable ones.
Exact start of the gun production is unknown, but it ended in second half of 90's when the creator was captured by the police. The final number of produced guns is also not known, although it could be in few hundreds, since that some of the captured ones were stamped with serial numbers (which is very uncommon for homemade guns) exceeding 300 (found on the pistol grip).
One Avenger SMG and its owner was eventually found by the police (Royal Ulster Constabulary), supposedly, after they hired an unknown air equipment company to make the suppressors for the gun, describing the product to them as some kind of an industrial muffler, and the manufacturing process was eventually connected and traced.
The "Avenger" is a homemade submachine gun chambered in 9x19mm, with a side folding stock that doubled as a front grip when folded, a suppressor, and a vertical magazine well. It uses a square pipe as its receiver.
The weapon is open-bolt, lacks a safety and is full-automatic only. The bolt is a wrap around barrel type with a forward recoil/return spring. In the rear section, there is a heavy coil spring that acts as a buffer. The ejector is replaceable with two screws.
The barrel lacks rifling but this can in some cases possibly increase ballistics at close quarters as bullets are more likely to tumble and cause greater tissue damage to unarmoured targets. Suppressor is screwed on the barrel and is a sealed unit with a ported tube for 3/4 inches of its length and the final 1/4 is baffled.