The development of the HK CAWS started in response to the JSSAP requirement for Repeating Hand-held Improved Non-rifled Ordnance (RHINO), which itself grew out of the Special Operations Weapon (SOW) project. RHINO specified a magazine capacity of 10 rounds, a requirement for the new ammunition to be incompatible with commercial 12ga shotguns, that felt recoil to be no greater than a Remington 870P firing M162 or M257 buckshot cartridges and that the system provide penetration and incapacitation capability significantly better than M162 and M257. In response Olin and Winchester developed a belted brass cartridge, containing 8 tungsten alloy pellets fired at and capable of penetrating pine or mild steel plate barrier at 150 m. These cases were also capable of being loaded with 000 Buckshot or with flechettes. Olin, in support of HK's CAW, also offered a fléchette load, using twenty much smaller projectiles at a high velocity of approximately