I'm going to weigh in on this: http://www.wideopenspaces.com/22-vs-shotgun-squirrel-hunting-great-debate/
I think the best one is whatever you want to use. I have a 12guage…I enjoy killing squirrels with it. I have a 22lr…I also enjoy killing squirrels with it. My favourite, by far, is to use a 410 that was my dad's from when he was a teen. But, they all work, all are lethal, and all allow me to enjoy those yummy scrummy tree-rats
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