AAT M.52 / Mod. F1 machine gun (France)

AAT M.1952 machine gun in light role, on bipod, left side

AAT M.1952 machine gun in light role, on bipod, right side

AAT M.1952 machine gun in medium role, on tripod

Caliber 7,5mm French (AAT-52); 7,62mm NATO (AAT F-1)
Weigth ca. 10 kg on bipod with light barrel; ca. 23 kg on tripod with heavy barrel
Length 1245 mm with long (heavy) barrel
Length of barrel 500 or 600 mm
Feeding belt 50 or 200 rounds
Rate of fire 700 rounds per minute

French armed forces got their own universal machine gun in 1952 with adoption of the AAT Mle.52 (Arme Automatique Transformable Modele 1952, or transformable automatic weapon model 1952) machine gun in 7.5mm caliber, developed by MAC (Manufacture d’Armes de Chatellerault). It was tested against several other designs, including a MAS M1950 prototype, a gas-operated universal machine gun with combination box magazine / belt feed. AAT M52 is a slim-looking weapon of indigenous design, available in a number of versions (light infantry on bipod and with light barrel, medium infantry on tripod and with heavy barrel, vehicle with heavy barrel). It was not without certain flaws, however, the most important being its retarded blowback action, which is sensitive to headspace adjustments and the timing of the bolt / retarder group. This gun, along with the older M1924/29 light machine gun, served with the French army through the Indo-China and Algeria campaigns, and is still the primary universal machine gun of French armed forces. With the transition to the NATO standards, the M52 machine gun was adapted to the 7.62x51 NATO ammunition, and got re-designated as AAT F1. The AAT M52 / F1 guns are now old, and at the time of writing France had expressed interest in acquiring a replacement GPMG. It seems probable that this will be a foreign design.

The AAT Mle.52 is a retarded blowback operated, air cooled, belt fed, automatic machine gun which fires from an open bolt. Barrels are quick-detachable and available in two versions – “light” (intended for the LMG role) and “heavy” (intended for sustained fire role).

The AAT Mle.52 uses a modified delayed blowback action originally designed by Pal Kiraly before WW2. In this system, the initial opening of the bolt is retarded by a lever which is installed between the light bolt head and the relatively heavy bolt body. When the bolt is in battery, a short arm of the lever rests against a recess in the receiver wall, and the long arm rests against the bolt body. Upon recoil, this lever, which is attached via a pivot to the bolt head, rotates to accelerate the heavy bolt body relative to the bolt head, thus slowing down the initial movement of the bolt head. Once the pressure in the barrel is low enough, the retarding lever exits the recess in receiver, and the bolt group continues its recoil cycle as one unit, extracting and ejecting the spent case on the opening movement and then loading and firing a fresh cartridge if the trigger remains pressed. To assist reliable extraction, the gun has a fluted chamber. While this locking system is relatively simple, it is quite sensitive to headspacing and also permits a lot of fouling, created by burning powder, to get inside the receiver.

The belt feed is more or less a copy of the German MG 42 feed, and is operated by a stud on the top of the bolt body. Feed is from the left side, using disintegrating belts with open pockets. In the 7.62 NATO version, this gun uses American M13 links.

Standard furniture includes a telescoping butt, made of stamped steel, a stamped steel pistol grip with plastic grip panels, a carrying handle and a folding bipod, both attached to the barrel.

In the light role the AAT Mle.52 can be fitted with an optional rear monopod; in the sustained fire role, it is installed on a modified US M2 tripod using a special adaptor with traverse and elevation mechanisms. It must be pointed out that while the barrel change procedure for the AAT Mle.52 is quick in theory, in practice it could be less comfortable when the gun is used from a bipod. Since the bipod is attached to the barrel, the gunner has to hold the gun in his hands while his Number 2 replaces the barrel. When the gun is used from more substantial mount, i.e. tripod or vehicle, this is no problem as the mounting via the receiver supports the gun.