I just spent a lot of time researching rimfire optics for my CZ 455 Tacticool, and ended up buying a Mueller APT 4.5-14x40. This is a big scope for a .22 (30mm tube), but I wanted something with enough adjustment to get me way out there (for a .22). I was ringing steel out to 200 yds with boring regularity two days ago. Needed 22 MOA of elevation with CCI SV to get there! All this to say, I learned a lot about what to look for. Adjustable objective is important if you plan on shooting up close, and far away. Most fixed parallax rimfire scopes are set for 50 yds I believe, with most standard rifle scopes set to 100 yds. At low power, you're not really going to "see" a difference, but with higher magnification the adjustable objective will allow you to remove parallax and clear up your image. I can focus mine down below 10 yds, and remain on 14x if I choose to. For squirrels at 80 yds, I would say a 2-7 or 3-9 would be okay, depending on how precise you wanted to be. These are kind of the standard magnification ranges for variable power rimfire scopes, and are typically pretty compact. As for the BDC reticles, finding one that meshes up with your ammo enough to be minute of squirrel reliably at 80 yds will be a feat. Nothing wrong with them, but it will take a lot of trial and error to find your holds and execute them reliably on a target that small. All this to say, you might be better off zeroing your scope at that distance or dialing for elevation since it's a fixed distance.

I think you'd be happy with any of the rimfire scopes from the major players. Nikon, Leupold, Bushnell, Burris etc... Don't discount the Mueller APV or APT scopes either, I've been very pleased with mine. Just look at the features and magnification you want, and work within your budget. Sorry for the long winded post!

A lot of guys don't think a premium scope is worth the expense for a rimfire rifle and that's their choice. For me, the rifle needs to VERY accurate, and such rifles are worthy of topnotch optics.

YMMV.

I'm no expert, but I use a "real" rifle dcope. I have an old Weaver K4 on my .22 and it shoots 1 inch groups at 50 yds. Probably do better if I could see.