The 6×45mm SAW describes an experimental series of rimless bottlenecked intermediate cartridges developed in the 1970s for the U.S. Army.

Eventually, the 5.56mm was retained and only the machine gun portion of the SAW (Squad Automatic Weapon) competition was successful.

[2] During the 1970s, the U.S. Army was looking to develop a new squad automatic weapon (SAW) that was lighter than the M60 machine gun with an effective range out to 800 m (2,600 ft).

The relatively heavy bullet combined with a moderate velocity had optimum long-range performance.

6×45mm SAW cartridges depending on their case materiel and bullet weigh 10.6 to 15 grams (164 to 231 gr).