Military long-range sniper rifles are often chambered for .300 Win Mag. Why don't we read about any chambered in .300 WSM or WSSM? I might speculate that the inherent accuracy advantage of a shorter powder column is somewhat negated by the longer cartridge being inherently (that word again!) more able to chamber consistently than the shorter cartridge.
I think you're overthinking it.
First point, and not a major one, is that the short case advocates will tell you how the shorter case is more "inherently" able to chamber more accurately than the longer one....
Biggest point why you don't read about WSM WSSM sniper rifles is the Military and its priorities. Remember that when the military goes outside its usual stuff, and buys "off the shelf" it is to perform a specific task. And, when they get that, the don't buy "new and improved" stuff. They may look, but they almost never buy.
Those sniper rifles in .300 Magnum were done and accepted a long time before the WSM WSSM rounds existed. Even when made today, the specs were set back then.
Could they have used the new short magnums? Sure. Pretty sure they tested at least a few. But then it comes down to MONEY. AND performance. If you've already got (and paid for) something that does the job well enough, its really tough to justify spending money on something else, UNLESS there is a clearly obvious and consistent advantage to the new round/rifles.
IT may be the short magnums are "inherently" more accurate than the longer ones, but unless the difference is considered significant enough of an improvement, they won't be buying any.
