I believe there was previous thread from a little while ago about this very question. People with way more insight and experience on this than me on the topic weighed in and one suggestion (for revolver) was the CCI 36grain MiniMag HP. Long story short of the video clip indicated while HP for .22LR doesn't really mean much since there isn't enough velocity (correct me if I'm wrong) to actually fragment, this specific round on average compared to the rest of the others had on average 11.5 to 12 inch penetration in gelatin.
The video is approximately 10 minutes, and while the "testing" done in the video is in no way comparable to NIJ, it was an interesting comparison between a variety of .22LR rounds.
Speaking only for myself,
If I’m choosing a 22 auto loader then I’m goin for whatever loads cycle most reliably.
In my case, my g19 AA22 conversion kit is very reliable with CCI mini mags. If I keep it relatively clean and oiled.
As for velocity, copper/lead, grain weights, hollow point or not, doesn’t matter as I see it. As long as it goes bang. Somebody wiser said something along the lines of “know what the limitations of your gear”
Whatever load works, I’m betting it could prove to be quite the eye irritant.
Lucky gunner did a whole series of testing with .22lr. If you are using it in an auto I would agree with MOT and use whatever cycles the gun well above anything else. Here is at least a list to give you an idea how different rounds might perform so you have somewhere to start looking.
I’ve been attempting to entertain the idea of carrying a Ruger MK IV 22/45 with a Surefire Ryder attached. Having a heck of a time finding a ‘proper’ holster that will allow the carry of a suppressed pistol though, and that’s hindering the project.
But when it comes to ammo selection... I found out quickly that a plated bullet is preferable to keep the gun and the ammo itself functionally clean. At pistol velocities a hollow point did not seen to be much of a benefit, and perhaps could be a hinderance by limiting penetration. I could not get very good accuracy out of the speciality type sub-sonic suppressor ammo, although it did function well and it was definitely quiet. I ended up settling on plain old CCI Mini-Mag 40gr solids. Recon I tried about 20 different loads to teach this conclusion.
Now if I can just find some way to carry this pistol with me...