I was investigating building an AR10 in 300wsm when I came across information on the 300 Rem Short Acrtion Ultra Mag. The round "seems" to be a better design than the 300 wsm but now appears all but vanished. Im curious as to why it didnt catch on....poor marketing, poor "real world" performance"....whats the skinny on it? You all far more in the know than I am so I figured I would ask.