So I heard it was Fire arm Friday and...

Colt House "Cloverleaf" revolver.

The first Colt revolver to use metal rimfire cartridges. It gets its nickname because of the distinctive shape of its four round cylinder

Greener police shotgun.

The Greener gun was made as a riot control and police gun in British colonies such as India. It was made using the obsolete but simple and robust martini-henry single-shot action and used a brass 14 gauge shell unique to it. This was to prevent it from being used effectively by criminals and colonial subjects.

Japanese Type I submachine gun.

An early Japanese submachine gun designed by Kijiro Nambu. Developed in 1938, it was one of the first ever submachine guns to have the magazine in the grip. The type I had an impressive capacity of 50 rounds, but never saw widespread use.

General Liu rifle.

An early design for an indigenous semi-auto rifle, named after its designer, General Liu of China. The rifle was adopted and set to enter production, but Liu's death kept it from entering widespread production.

Bergmann-Bayard 1910

An early semi-automatic pistol chambered in 9mm Bergmann. It fed from a 6 to 10 round box magazine housed in front of the grip. It competed with the Luger and Mauser c96 in a number of military trials.

It was adopted by the Dutch military and used until its replacement by the Browning Hi-Power in 1946

A Mauser K98 rifle cut down into an 'Obrez' pistol. It was used by Czech partisans during WWII, with the grip taken from an MG42.

Girandoni Air Rifle

A very advanced air rifle designed in 1780 and used by the Austrian military. The Girandoni was a repeater using the airtank that formed the rifle's buttstock to propel a .46 caliber ball. It had a 22 round magazine and could fire all 22 shots in the span of 60 seconds, compared to the single shot muskets contemporary with it.

It was also used in the Lewis and Clark expedition

Clair 1893

An early French semi-automatic pistol. Instead of a short-recoil mechanism used by most early semi-automatics, it used a unique gas operated system. It had an internal six-round curved magazine in the grip, which was loaded through a gate under the chamber. It was used in a French military trial where it was rejected due to problems with gas leakage and failure to feed.

Polish Błyskawica

The Błyskawica was manufactured on an entirely clandestine basis by the Polish Home Army during WWII. It was the first ever Polish-made SMG design to be mass-produced and under very difficult conditions. It's a straight-blowback design chambered in 9mm luger. The weapon was simple to the point of crudity, but reliable.

China Lake Grenade Launcher

A pump action repeating grenade launcher developed by the China Lake Naval Research Facility. Its tube magazine held 3 grenades with one in the chamber making 4. It was deployed to a few Navy SEALS units but was adopted too late to be used in the Vietnam war. Few examples are known to exist.