All of these are from www.brassfetcher.com
-- a fascinating resource page. Let's see what a top-shelf .22 hyper-velocity load can do on ballistic gel, with an eye towards a self-defense comparison.
First, let's calibrate our expectations -- here is a 124 gr. 9mm Hornady XTP hitting a block of gel:
and a .22 CCI 40gr subsonic segmeted load:
-- pretty much no comparison at all. Different ballpark in every way.
However, now let's look at CCI Velocitor out of a handgun:
And finally, CCI Velocitor out of a rifle:
My take-away is that, loaded correctly, a .22 rifle can be surprisingly similar to common self-defense handgun performance. The Velocitor expands immediately to maximum diameter, holds together, and penetrates at least as far as the above 9mm.
Out of a pistol, you still get immediate maximum expansion and excellent penetration, though it looks significantly less "devastating" to the gel (whether or not this part matters is debatable, I guess).
Obviously, I'm not going to switch to .22 for all my self-defense needs, but I'm not going to under-estimate the capability of these things, either. I'm pretty sure a properly loaded .22 could be used to open up a serious world of hurt on home invaders, not so different from a combat handgun.