We'll start with the 1895 Nagant Revolver, this was the official sidearm of the Russian Imperial Army from 1895 to 1930. You have heard of single action revolvers and double action revolvers.....the Nagant is a "triple action" revolver. Pulling the trigger advances the cylinder, cocks the hammer and moves the cylinder forward to seal the gap between the barrel and the cylinder
Here is a picture of the ammo this gun shoots, the 7.62 x 38mmR, the bullet is encased completely in the brass case, when fired the brass case seals the gap, which aids velocity
The infamous P-08 Luger, adopted by the German Army in 1908 it was the 1st pistol chambered in the then new 9mm Parabellum round. It is unique because a real German Luger is still a somewhat rare find and the design of the pistol (the action) has never been duplicated (probably because it didn't work that well).
This is the Sedgley OSS .38 "Glove Pistol" You may remember seeing this used against the Nazi guards near the end of the movie "Inglorious Basterds" The idea was to punch the victim in the gut, in the movie (typical of Tarantino) the Nazi was punched in the forehead!
This is the FP-45 Pistol, FP stood for "Flare Pistol" which is what the US government told the contractors they were building, instead these were single shot .45 ACP pistols designed to be dropped behind the German lines to aid resistance forces in killing Nazis and taking their guns. The gun had 6 rounds hidden in the grip, it also came with cartoon instructions
The U.S. Army tried this concept again during the Vietnam War, this time they called it a "Deer Gun"
How about a revolving shotgun?
The Taurus/Rossi Circuit Judge is not technically a shotgun (it has a .452 rifled barrel) it can chamber & shoot the .410 shotgun round
Here is the Colt Defender Mark I, 8 barreled Shotgun, 20 gauge 3" magnum chambered semi-auto.
Here is the COP 4 shot derringer pistol, a four barreled gun with a double action style striker mechanism. This was based on an early design by Mossberg, called the "Brownie"
Here is a unique revolver designed by Karel Michalek from Czechoslovakia (now the Czech Republic). The gun is definitely exotic.
some people may consider this a weird choice, but I feel like the Desert Eagle pistol is unique, it is a semi-auto, gas operated and has a rotating bolt normally only seen on rifles and was made in Israel in addition it has been used in over 500 movies....obviously Hollywood thinks it is exotic!
We could devout a whole page to big bore/African/Safari rifles. I'm sure you've seen those before, but what if someone were to build a handgun to chamber those humongous cartridges? The Pfeifer Zeliska Revolver is chambered for the massive 600 Nitro Express, in a rifle this cartridge is only for "real men", in a handgun, it goes beyond the ridiculous.
another picture to give you perspective:
This bad boy shoots the venerable 50 BMG round.....this prototype was on display at the 2004 SHOT show, not sure if they ever went into production though
Ever seen a semi-automatic revolver? The ill-fated Metaba revolver never made it very far. Recoil operated the mechanism which rotated the cylinder and cocked the hammer, essentially making it a "single action semi-auto revolver"....It was also unique in that it fired from the bottom chamber, the idea is that the bore axis would present less leverage on the shooters hand
Based on some of the design principles of the Metaba, the Chiappa Rhino also shoots from the bottom chamber, it also had a weird six sided cylinder.
Here is what the complicated mechanism inside the Rhino looks like
another innovative revolver design was the Phillips and Rogers Medusa revolver. Externally it looked like a S&W Custom Shop K frame. While the gun may have been inspired by the S&W DA revolvers, the key design was in the cylinder and ejector. The Medusa could chamber, 38 S&W, 38 Special, 357 Magnum as well as 9mm Luger, 9mm Makarov, 380 ACP. 38 Auto/Super etc... basically any cartridge with dimensions smaller than a 9mm's .392 case and bullet diameter in the .355-.358 range. The guns are quite rare, supposedly only 250 were sold in the U.S.
Fabrique Nationale (AKA FN or FN Herstal) has come out with some interesting designs, Here is the FN F2000 is a bull pup rifle firing the 5.56mm NATO round, it is smaller and lighter than traditional AR style rifles yet it accepts standard STANAG 4719 magazines (AR mags)
The FN P90 is a bull pup, select-fire Personal Defense Weapon. It was designed to replace the MP-5 and Uzi as a security detail weapon with more range and killing power.
The magazine of the P90 mounted on top of the receiver in a horizontal fashion, here is a picture of it below, it also as a strange grip angle & trigger
It fires a new and unique cartridge, the 5.7 x 28mm, this is a small version of the 5.56mm NATO round. Slightly larger diameter, with a shorter case so it can be used in pistols as well, here it is compared to the 5.56 and a .38 Special
Here is the FN pistol designed to shoot the 5.7mm, called the Five-Seven, it is unique in that the double stack magazine can hold 20 rounds when fit flush, an extended 30 round mag is available as well as a 10 rounder for those living under communist regimes
Using a similar idea as the Five-Seven, except using a readily available (although much weaker) cartridge was the Grendel P30, it fired the .22 Magnum rimfire cartridge from a 30 round magazine in its grip frame
After Grendel went bankrupt, the designer of the Grendel P30, George Kellgren, founded a new company called Kel-Tec. Kel-Tec redesigned the Grendel P30 into the Kel-Tec PMR 30, again carrying 30 rounds of .22 mag
Kel-Tec has been instrumental in bringing other unique designs to the American Gun Market, The KSG (for Kel-Tec Shot Gun) is a bull-pup pump shotgun with twin 7-round tube magazines. It holds 15 total rounds and is shorter than a standard pump shotgun. They added a selector switch so the user can decide which magazine to feed from.
The KSG was not completely original , the concept was taken from an early design known as the Neostead from South Africa
Similar to the FN P90 the Calico M960 is available as a pistol or rifle and in semi-auto for the GP and full-auto for LEO markets. It uses a helical magazine that is mounted to the top of the receiver and comes in 50 or 100 round capacities.
They also make a .22 LR version known as the M-100
More exotic bull pumps that fire the 5.56mm NATO round:
The Famas G-2
The Steyr AUG
in the past we have seen people connect two Ithaca model 37 shotguns together, we even saw the contraption below, the Remington 1740, which is a left hand and a right hand Remington 870 shotguns bolted together to create one bad-ass shotgun
This concept was taken to the extreme with the creation of the Gilboa Snake Rifle. Designed and built in Israel, it is basically two AR rifles (a left hand & right hand) fused together. The magazines are standard mags with a connector, the controls are ambidextrous. Think double-tap with only the recoil of a single shot fired.
Again taking the double concept to a new level, the Arsenal Firearms 2011A-1 is two 1911 pistols fused together (again a right hand and a left hand). They feed from mounted magazines that share a floor plate (siamese style).
Some modern exotic guns from around the world, here is the PP2000 from Russia
The Steyr TMP from Austria
The ST Kinetics Sub Machine Pistol is made in Singapore, it is unique in that the 30 round magazine and back strap of the grip are made from translucent plastic allowing the user to determine the ammunition level in the gun without removing the magazine
The KRISS Super V uses Glock Magazines and a unique bolt arrangement that angles down as it moves rearward.
in the roaring '20s gangsters would outfit bags, briefcases and boxes to fire fully automatic guns without removing them from their enclosure, here is a modern day version
A variation on this theme is to make a normal object transform into a gun, like this flashlight that unfolds to become an SMG:
Same idea, pen guns have been around for awhile, most of them shoot the .22 rimfire
Special thanks to Wikipedia, Arsenal Firearms, Gilboa, NRA Museum & Airborne Combat Engineer for some of the photos