Hi Wayne,
I have several 22's that I use 55gr. in, the best is a Contender 10" Hornet. It'll run 2300 fps and group right at MOA out to 200M. My Handi rifle also works very well at 2500 fps, but has iron sights so not sure of its ultimate grouping ability. But it goes where you point it every time. Both of these guns have 1:12 twist. I used to have a heavy barrel AR15 that I set up as a straight pull bolt rifle. It had 1:8 twist, and would shoot very accurately (sub MOA) up to 1750 fps. Beyond that it went to heck in a hurry. I also had a Sako hornet rifle with 1:16 twist. It would only stabilize a 40 gr. bullet, and never did shoot very well. I got it down to 2 MOA with one load, but it was the pickiest thing I ever worked with. I also cast the RCBS 55gr. bullets for a friend with a 22-250 that has a 1:14 barrel. It shoots very well up to 2600 fps out to 200M. (We shoot a cast bullet silhouette match on half scale targets to 150M, so get lots of trigger time with various cast bullets.) From what I see, the medium weight bullets, 55-60gr. in medium twist barrels (1:12) seem to be the way to go for best performance. My next 22 cast bullet shooter is going to be a 222 rem with 1:12 tube, I should be able to run pretty close to full throttle with that one with a good quality barrel and proper throating.