What's the name, Quick Shok, or something like that? I got some from Cheaper Than Dirt and tried on on a rock squirrel in my yard. (Same size, basically as the reds and grays across the south.) At about 15 yards, he reacted more like he'd been hit with a .22 Hornet...The bullet splits into three parts, it sez, and does Bad Things. I didn't do an autopsy, but it was instant-gone for the squirrel.
The CCI MiniMags are accurate in one of my .22s, and they do well on squirrels.
FWIW, Art