Hey there:
The best practice load and my absolute favorite squirrel load in:
1-22 Hornet
2-221 Fireball
3-222 Rem
4-223 Rem
This load will shoot all day in one hole from any of the above. I have chrono'd it many times. My goal was to duplicate the 22 rimfire in velocity, which this is about as close as you can get.
This load is 4.5 grains of Red Dot powder with the 55 grain FMJ, (read cheapest I can find). With this load, I killed 22 big ole fox squirrels with one shot each, at various ranges, tree top to less. This load does not leave you with a 2 piece squirrel to skin out like some of the other bullets.
This load kills instantly even a body shot. That one year that I killed the 22 Fox Squirrels, I had to do something. They and the crows were eating us out of house and home. We have pear and fig trees, and also pecan trees. Sure good eating, a squirrel fattened up on good fruit and pecans.
I've used this load about 15 years, now. Also great armadillo load. Shoot him any way, he is ripped.
casper_zip