Red Rider bb will penetrate squirrel hide and kill ‘em.
I call BOGUS on the Red Ryder claims, unless I had a wildly underpowered version in the many years I owned and enjoyed all sorts of affordable air rifles. Oddly enough it’s the little things that make the difference - for instance there are “cheaper” Crosman pump action models which I found to be more accurate as a boy due to their “tighter” back sights and thinner sight-blades. Also well in the affordability range are the finer one-shot all-wood .177 chinese-made models with adjustable sights and even included scopes! I have one whose name escapes me but it is a fun piece and well within the power range to put down a varmint within two hundred yards. And... I think I got it at Wal-Mart!