Make sure to get at least a 20X scope as you don't want to be in their attack range if not a clean kill. The 444 necked 500 does make an intresting chamber
Depends on time of year and the condition they're in. In the spring you should be able to just rub a little Imperial Gopher Wax on their necks and shove em in there. You should be good to go, unless while your inspecting their necks you notice they really seem to be bent out of shape (this happens sometimes due to rough handling)... In the fall sometimes their basses get a little fat and you might need to full length resize em first.One more question. How do you intend to stuff these squirrels into the chamber once you've decided on the bore diameter?
Oh good god man, if we're talking red squirrel defense, staying at home with your head under your pillow isn't going to save you! You've got to cowboy up! Protecting yourself at home is the paramount goal here! These little bass tards are worse than Reavers! In an hours time they'll unzip you and have your owens corning pink hanging in trees for half a mile in every direction! If you have time for surgical precision, sniping their scouts outside the perimeter with CCI CB's can be effective, but once they've targeted your position / if you're outnumbered, the only viable defense is to fall back and try to hold them at the wire, and the 444 isn't the best tool for that job. If they breach your perimeter en mass all hope is lost, but if you can keep up with them as they come through the wire, I've found that the best weapon is the 12 gauge Winchester Target Load launched from a short pump gun. In close quarters it will literally vaporize the little bass tards.I think I'd just play it safe and stay home if all I had was a 444.