I used to hunt squirrels with a 760 fps sub-sonic .22 long rifle, out of a Ruger 10-22.
Head shots at 30 yards, thru and thru.
Also, I know for a fact that they will penetrate about the first 60 pages of a CAIR-supplied quran, at about 20 feet.
How was the reliability? I've read that sub-sonics aren't the best thing to use in semi-auto rifles.
Nice shootin’.