I traded into a mark 1 .22 cheetah awhile back. We loaded up some 52 grainers and stepped up to the chronograph with much anticipation only to be let down. We renamed it the .22 housecat. I was only about 120 fps faster than a regular 22-250. I did have some very interesting results loading superformance powder in a 22-250 improved version though. We loaded 70 grain Berger's and superformance powder in a rifle that has a 27" barrel and a chamber half way between an ackley and a stock 22-250 case. We chronographed 3600+ fps and loaded the same brass 4 times. Never had a sticky bolt and brass was still good all the way around. We loaded up incrementally at least 6 times before we reached that velocity. I will say one thing about these high speed fast twist barrels wipe out used often is your best friend.
