You have a lot of nice rifles!
In the 27 years that I've lived in Nebraska, I have yet to encounter another tree squirrel hunter in either Kansas or Nebraska, but have run into a couple in northwestern Missouri. Among the things that I like about tree squirrel hunting is that the seasons tend to be very long, in Nebraska it runs for six months, from August 1st thru January 31st, and tree squirrel hunting is typically done in a spot and stalk mode in, or on the edge, of timber, so it is good practice for still-hunting whitetails.
Since 2007, I have done the majority of my tree squirrel hunting with a couple of 17HM2s, Marlin 917M2/917M2S and Savage MarkIIBVSS. I recently bought an Anschutz 1502 and am hoping to take it out once before the tree squirrel season ends.
I was surprised to see pictures of grey squirrels, as I don't recall seeing any species except for fox squirrels in Kansas, Nebraska, and northwestern Missouri.
