In my 10/22's Remington SS or SSS's work well, it's Sub-Sonic, but I swear there's a third S for some reason. It's been a year or two since I've used them. I think they're named Cyclone SS's or SSS's. Anyway, they worked fine, I used them in Marlin 60's old Marlin 99's (basically a Marlin 60 Carbine made to look like a M-1 Carbine), a Ruger Mark II pistol, Jennings J-22 pistol, and my three 10/22's. I've also used them in a Win 55 and an anschutz, which don't really count since they're bolt guns.

They're VERY quiet, and they were very accurate for all of my guns. They're relatively cheap as far as "specialty ammo" goes. They got plenty of penetration as I used them for coon hunting over hounds at night, they'd penetrate just as well as the CCI minimags that my dad uses (hyper velocity rounds, GREAT rounds, but expensive and really loud in my "little guns").

Ely match ammo (red box) is pretty expensive, but it also gets the job done VERY quietly (and it's MUCH more accurate than your 10/22 will EVER think of being). It costs about $5 a 50rnd box where you can find it though.

Biggest problem with subsonic (quiet) ammo is that it is slow, they've got TERRIBLE trajectories, and are often very badly effected by any wind. If you're just shooting squirrels and rabbits in your garden, buy some $9/550rnds Remington Gold bullet Bulk packs from walmart, they're plenty quiet, but they've got enough stank to be accurate and flat shooting, and get the job done when they get there.

Why don't you just use some standard velocity ammo? I don't care where you live, if it's legal to shoot out there, your neighbor can't complain much unless you're shooting "excessively".

Are you thinking of Aquila SSS ( Sniper Sub Sonic )???