Depends.
I'd suggest Simmons .22 mag 4X for guns that are mediocre accurate for short range use. I had one on a 77/22 all weather .22 mag for a while. It got the job done but there were times I felt the need for a little more magnification.
Leupold 2-7X RF special is pretty nice for a little nicer gun. So is their EFR version of the 3-9X compact.
I put a Burris 4-12X AO compact on one rimfire I had. I was not happy with that scope. I couldn't focus such that it was clear at more than one distance, so I had to use the AO to compensate for focus changes with distance rather than for parallax adjustment. It had a lot of curvature / distortion even well away from the edges of the sight picture. And it was way heavier than it's physical size warrants ... same weight as my Leupold full size 6.5-20X.
I'm currently running a Leupold VX II 4-12X on a heavy barreled Ruger 77/17 HMR. Probably don't need quite that much but it's nice when trying to pick out squirrel parts or squirrel eyes when they are hiding in grass clumps.
Tom
