Developed by Winchester in the 1960’s and registered with SAAMI on 7/1/1965. It utilized a 200 grain jacketed soft point projectile. Was developed for the M1894 Winchester action to enhance the performance of available cartridges. The cartridge was never commercialized and only unheadstamped original versions were produced by Winchester.

The middle version is a dummy and the third version was made by Ken Stewart in South Africa.

.408 Winchester Dimensions Inches Millimeters
Bullet Diameter .400 10.2
Rim Diameter .506 12.9
Base Diameter .446 11.3
Case Mouth Diameter .430 10.9
Case Length 2.030 51.6