If anyone finds images of unknown/uncommon type rifles and machine guns, Post them on this thread.

To start with, Here are some.

APS underwater assault rifle (Russia)


APS rifle, with butt collapsed; note crude non-adjustable iron sights and unusual magazine

Caliber: 5.6x39 mm MPS
Action: Gas operated, rotating bolt
Overall length: 823 mm (butt retracted), 615 mm (butt collapsed)
Barrel length: n/a
Weight: 2.4 kg less magazine; 3.4 loaded
Rate of fire: 600 rounds per minute (in air)
Magazine capacity: 26 rounds
The APS (Avtomat Podvodnyj Spetsialnyj = Special Underwater Assault rifle) was developed during the early 1970s at TSNIITOCHMASH (Central Institute for Precision Machine building) by the team lead by V. Simonov. APS has been in active service with combat divers of the Soviet and Russian Navy since circa 1975.
The APS is designed for special underwater cartridges, which fire 5.66 mm needle-like projectiles 120 mm long. The projectiles are stabilized using a hydrodynamic cavity, generated by the flat point of the projectile. The cartridges use standard 5.45 x 39 cases, sealed from water. The APS itself is a relatively crude, smoothbore arm, with a gas operated, rotating bolt action, fired from an open bolt. Single safety / selector switch is located at the left side of the receiver and allows for single shots and full automatic fire. The gas system features a patented self-adjusting gas valve, which allows the gun to be fired both underwater and in atmosphere. The simple trigger unit allows for single shots and full automatic fire. The rate of fire under water, as well as the effective range, depends on the actual depth. Sights are crude: a non-adjustable open notch rear and post front. The retractable buttstock is made from steel wire. The most complicated thing in the whole design is the feed system, which includes several parts to avoid double and even triple feed with the extremely long projectiles. Unusually deep (front to back) magazines are made from polymer and hold 26 rounds.
It must be noted that while APS could be fired "above the water", it should be done only in the case of emergency. According to the available sources, the expected service life of the APS when fired "in the air" degrades severely, and the effective range is limited only to several tens of meters. So, the APS is useful only under the water, where it is quite efective. --

I have seen the MAS 54 series, there is at least one in the military museum in Les Invalides in Paris

Was the MAS 54 ever issued? It looks familiar.

Originally Posted by senojekips

Was the MAS 54 ever issued? It looks familiar.

No, the design was rejected. The French Army stayed with the MAS-49/56 until 1979 when the FAMAS was introduced.

The fourth picture down one was made by "Fuzzbean" on the home gunsmith forums. It was not safe to fire though and was given to the NRA.

Originally Posted by PaulS

The fourth picture down one was made by "Fuzzbean" on the home gunsmith forums. It was not safe to fire though and was given to the NRA.

I saw that firearm in Person at the NRA National Firearms Museum.

Second and Third pictures were of the prototype rifles that were designed to replace the AK-47 during the 1950s. They worked but the Soviet Army later changed their ideas.