Avenger submachine gun

The Avenger is an submachine gun of British origin that was made during the 1990's in a garage of a private individual's machine shop near Belfast, Northern Ireland.

Background
Supposedly the loyalist paramilitary group that used the guns was eventually found by the Royal Ulster Constabulary (RUC) after they hired an unknown air equipment company to make the suppressors for the gun, describing the product to them to be used on some kind of industrial exhaust system, and the manufacturing process was eventually connected and traced.

Exact start of the gun production is unknown, but it ended in second half of 1990's when the creator was captured by the police. The final number of produced guns is also not known, although it could number in the hundreds as some of the captured ones were stamped with serial numbers (which is very uncommon for homemade guns) exceeding 300.

Overview
The Avenger is a fairly simple "home-made" submachine gun with side folding stock, silencer and a vertical magazine well. It is a "Square Section" gun, meaning it uses a square section mild steel pipe as its receiver, other parts (magazine well, trigger group, handle etc.) are also structural steel welded to the receiver.

It is fed from Sten magazines with a square version of the bolt used in the Sterling L2A3, but does not adapt Sterling submachine gun magazines. Usage of industrially fabricated magazines in "home-made" guns is very common (especially in the history of Ulster paramilitary groups weapons) as magazines of comparable reliability are difficult to manufacture.

The weapon is open bolt fired, lacks a safety and is full-automatic only. The mainspring has an interesting feature; in the rear section of receiver, there is another spring, heavy coiled, that acts as a buffer. The ejector is replaceable with two screws.

The barrel lacks rifling but this supposedly can in some cases increase terminal ballistics at close quarters. The 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. Exact dimensions of the gun were not published, but based on the existing pictures it could be speculated that the length with suppressor is approximately 75 cm, without a suppressor is 35 cm, and total length of the gun with both suppressor and protracted folding stock is around 1 meter.

The rate of fire is, based on the dimensions of the receiver and bolt design, probably no less than 900-1000 rounds per minute. Along with the unrifled (smooth-bore) barrel, this high rate of fire will no doubt further lead to extreme inaccuracy of the gun.