Defense Review was told that the KAC 6x35mm PDW cartridge weighs approx. 65 grains and yields 848 ft.-lbs of muzzle energy at 2425 fps out of the CQB's 10-inch barrel vs. 5.56x45mm M855 ball's reported 776 ft.-lbs of energy (unconfirmed/unverified) out of an equivalent-length (10") barreled M4/M4A1 CQB subcarbine/SBR (Short-Barreled Rifle). Even though the muzzle energy generated is higher, KAC claims that the CQB generates 40% less recoil compared to a 5.56mm AR-15/M16 subcarbine/SBR.
To give an idea of how the KAC CQB PDW/6x35mm cartridge combo stacks up against other PDW/ammo packages, it's been reported to DefenseReview that the standard FNH SS190 5.7x28mm round creates 390 ft-lbs out of a FNH P90 Submachine Gun/PDW (reported 10.2" barrel), and the standard HK Defense 4.6x30mm round creates 310 ft-lbs out of the HK MP7A1 PDW (7" barrel). When asked about the CQB's combat/lethality envelope, a KAC official told Defense Review that the CQB/6x35mm package is accurate and lethal out to 300 meters. The CQB will deliver sub-2" MOA.
The KAC CQB PDW is utilizes a dual-piston system and is gas-operated. The recoil spring runs the full length of the upper receiver, right up the middle between the two gas pistons. Bolt system is AKM/Kalashnikov style. The CQB utilizes a monolithic upper receiver and full-curve magazine. The barrel has been lightened with a patented dimpling process, which gives the barrel an interesting look.