I had a "Spark Plug" .350 Remington Mag as Col. Cooper called it. He used 250 grain bullets and so did I . The extra powder cap. over the .35 Remington did not get you much in a 18" barrel the 660 Remingtons had . I could only get 2400 fps in the mid 80s with mine with 250 grain spitzer bullets. The Remington only had .308 SA length and the bullets had to be deeply seated . The shortened belted H&H cases only held 3006 type charges with no bullet seated and when you deep seated the 250 gain bullets to fit the action, then you had a strong .358. Winchester. The WSM case looks promising, but not in a short action. If you want a hi velocity .35 you are gonna have to have a 30-06 length action to shoot 250 grain bullets. My .358 Norma does that with common H&H brass at .338 Win Mg length.. That .35 Whelan ackly Imp really look sweet. I would imagine 2800 FPS with 250 grain bullets from a 22"+ barrel are possible.