The 7mm Dakota is a "rimless" proprietary cartridge designed by Don Allen and based on the .404 Jeffery case shortened to function in standard (.30-06) length actions. This case is also offered in 300 Dakota, 330 Dakota, and 375 Dakota. Factory loaded ammunition is supplied only by Dakota. The 7mm Dakota uses standard .284" diameter bullets. This case has a rim diameter of .545 making it larger than the standard belted magnum cases. This case is 2.50" long and has a sharp 30-degree shoulder. The cartridge overall length is 3.33". 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.