The 300 Dakota is based upon a shortened 404 Jeffery case. In any given length cartridge, use of the non belted 404 Jeffery case provides about a 15 percent increase in usable case capacity, compared to the standard belted case. The cartridge provides a significant capacity advantage over the 300 Winchester Magnum and comes close to duplicating capacity and performance of the much longer 300 Weatherby Magnum. 

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