That is one heck of a big (I mean expensive) round for a squirrel! Have you not heard of the .17?

I am trying to guess what it is: it has a rim, about 2 inches long, so not a .22 WMR, bullet is small and blunt looks like .22 something, does not look like .22-250 (especially as it is rimmed as in a rimfire). Can you fill me in? Have you just won an inheritance, or the pools?
On another note, after removing all the squirrels in the adjoining woodland, the explosion in bird life has been phenomenal. Just counted 16 different species this morning straight out of my kitchen window, many including the thrushes, woodpeckers, gold finches and nutcrackers with two or more young. Never seen that number of young with adults before when the squirrels were here. There were a lot of squirrels, and in spring young birds or eggs were a daily diet based on the goey mess in their stomachs when I checked them.