So another interesting wildcat round based on the 5.56x45.
Quote:
Cartridge Specifics
The 7.62x40 WT is based on the inexpensive and readily available 5.56x45 Nato cartridge case. The 5.56 case is shortened to 1.560” and then re-sized (single operation) in a standard 7.62x40 WT sizing die which results in a formed 7.62x40 WT case with a finished overall case length of 1.565”. The cartridge is designed for 110-150gr .308” diameter bullets loaded to supersonic velocities, but if chambered in a 1-8 twist barrel is also suitable for heavy bullet subsonic use also.
http://www.wilsoncombat.com/762x40WT.htm