The WSM cartridges are just the next evolutionary step in cartridge design. The 300 H&H was 1st but was so long it needed a magnum length action, or a modified long action rifle. The 300 WM was designed to do the same thing (actually a bit more), but from a standard long action. The 300 WSM duplicated 300 H&H, but from a short action.
The WSSM's in my opinion took things a little too far. Short fat cartridges burn powder more efficiently and have proven to be a little more accurate. But the WSSM's are so short and fat they have always had feeding and other issues.
What about SAUMs--do they also burn out fast?
There is an interesting bit of history behind Remington's SAUM, and Rugers Compact magnum cartridges. A guy named Rick Jamison designed a 30 caliber wildcat cartridge he named the 300 Jamison and took out a patent on it. He took his idea to Winchester hoping to sell the rights to them to manufacture the cartridge. Winchester turned him down, but a few months later offered the 300 WSM cartridge, which was an exact copy of the 300 Jamison.
Jamison sued and won. Under the terms of the suit Winchester was required to make 300 WSM rifles and Jamison got a royalty from every rifle and box of ammo sold for a number of years. No other manufacturer was required to make them, but if they did they had to give Jamison a royalty.
Both Remington and Ruger made a handful of rifles chambered in 300 WSM before the lawsuit. After the lawsuit they developed their own short action cartridges that were enough different to avoid the lawsuit. Otherwise there would have never been a Ruger Compact Magnum or a Remington Short Action Ultra Magnum.
