And the RCM case is just an Imperial Magnum case. None of that stupid belt that is a throw back to double rifles. Should have gotten rid of that across the board years ago.
The belts were introduced to give positive headspace on rounds with long, sloping shoulders in
magazine rifles, not doubles, in a way that wouldn't interfere with feeding. Since handloading wasn't something even contemplated for ordinary humans, the potential issues caused by the belts weren't issues at all.
Doubles were chambered for the belted rounds later on, no doubt because the rounds were popular and effective, and ammunition was widely available in far-flung locations, unlike some of the old, proprietary rimmed rounds, many of which went out of production for a time.
Belted cases also made it easy for pioneering wildcatters like Roy Weatherby to develop their creations without having to contract out for special brass, which would have been difficult and expensive, possibly prohibitively so. Later on, Winchester, Remington, and Norma continued to use the same basic case, even though they were perfectly able to start from scratch. Since they were in the business of selling ammuntion, not catering to reloaders, it was a sound decision for the time.
