Hornady made the 6x35mm TSWG. TSWG (Technical Support Working Group) is a contracting pool for various agencies involved in anti-terrorist activities. Headstamp Hornady 6x35mm TSWG.
"6x35mm PDW
Designed entirely around a brand new short .243 caliber cartridge made by Hornady exclusively for KAC, the receiver/magazine-well section of the KAC/PDW is 1/3-inch shorter than those elements of the M4 and that includes the magazine. This because the overall length (OAL) of the KAC/ PDW 6x35mm cartridge is .32-inch shorter than that of the 5.56x45mm NATO cartridge.
The 6mm Hornady bullet fired by the KAC/PDW is of the open tip match (OTM) type and weighs 65 grains. This bullet is loaded in front of a proprietary propellant that was designed especially for the cartridge by Mr. David Emary, Chief Ballistician for Hornady Mfg. The 6x35mm PDW cartridge is based on a modified .221 Fireball case, which itself is a shortened derivative of the .223 case.
Fired from the 10- inch barrel, the 6x35mm sends its 65-grain bullet at 2,425 fps with an impressive 848 ft. lbs. This is almost as fast as the 5.56x45mm NATO bullet from a 10-inch barrel and has 74 additional ft. lbs. of energy. Compare this with 310-ft. lbs. for the 4.6x30mm cartridge and 390-ft. lbs. for the 5.8x28mm round. The 6x35mm PDW is a totally useful cartridge out to 300 meters. The 6x35mm cartridge can use virtually any .243/6mm bullet.
Currently, 20- and 30-round magazines exist for the KAC/PDW in prototype, and all have been completely machined from solid blocks of aircraft quality alloy in two halves and then welded together, and they are of unbelievable quality. However, production magazines will be molded from translucent polymer."
KAC