Remington and Winchester went to short, fat, unbelted cases for their latest 7mm magnums, the 7mm Remington Short Action Ultra Magnum and the Winchester Short Magnum. Both cartridges were designed to work through short action rifles. Both were introduced in 2001. The Remington version is based on the same case as the .300 SAUM, necked down to handle .284" bullets. The SAUM cartridges are based on the long .300 Ultra Magnum case, drastically shortened to work in special Magnum versions of the Model 7 rifle, which weigh between 6.125 and 7.25 pounds and sport 22 inch barrels. 

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