no matter what your linear velocity the rotational velocity should be the same
rotational should be 1 rev per 8 inches of travel no matter what the linear speed is. if the bullet can't stand up to the 1 rotation in 8 inches it will fail at 1000 fps or 3000fps just my ruminations.
i fired some 55's from a 30-06 using sabots at ground squirrels with a chrono speed or 4200 fps . they worked. stepped up to 4300 and there was a puff out of the muzzle. and my chrono got peppered.
yes they were speer tnt's ymmv
Nope. That relationship changes once the bullet leaves the barrel.
If you mean within the barrel then yes it stays one turn per eight inches. But how quickly the eight inches goes by, and hence how quickly the one turn goes by, does depend on the linear speed.
