These Are Not Your Father’s Shotguns

KS-23 

The KS-23 was the Russian Special Forces shotgun of choice. This pump action shotgun fired a massive 23mm round and is regarded as the largest shotgun in use today. The KS-23 is so large it has been designated as a carbine by the Russian military. 

The KS-23 was originally designed by Tula Arms Plant. The shotgun was first made out of repurposed aircraft guns, the plant took 23mm aircraft gun barrels and cut them down to a length suitable for shotguns. The aircraft gun barrels used had too many flaws to be installed on aircrafts but they determined that they were safe enough to use for shotgun barrels.