re: Update: 22LR Subsonic Ammo Question regarding a 10/22.

I went down that rabbit hole a number of years ago before getting a custom barrel w/ a threaded muzzle. A couple of observations:
1. In my standard 10/22 mags, anything other than 22 LR would not feed from the magazine. Specifically, the tip of the bullet of 22 shorts, 22 longs, etc would nosedive into the mag.
2. Ammo that was barely subsonic, e.g. CCI Standard Velocity (muzzle velocity 1070 fps), would reliably cycle my action. OTOH, ammo at the other end of the subsonic spectrum, e.g CCI 22 Quiet (mv 710 fps) wouldn't reliably cycle the action. There's a lot of other options in between those two. I'd first start w/ CCI Standard Velocity. As far as HP's, I'd try CCI Subsonic 40 gr HP and Aguila Subsonic 38 gr HP (both w/ mv of 810 fps) . CCI Standard Velocity ammo is the most accurate ammo in all my 22's. Plus it's usually more available than most of 22 LR ammo.
3. I've never changed out the recoil spring in my 10/22's.
4. Keep your action clean. Look up on the internet how to polish the 10/22 bolt. Here's one example.

Good luck. Keep us updated.