NOE's WFN out of my .221 fireball with some trailboss is my favorite squirrel load. Quiet and anchors them on the spot. If I have to be super quiet I use the CB rounds out of my Savage 22. I take a fine file and wipe the nose of the bullet to create a flat spot. The flat point reduced the number of squirrels running off with not immediately lethal holes in them.
The Paco tool has been on my list for a long time. Curious if that would help the CB rounds shoot better for me.