Any of the higher power HW guns (Beeman equivalents) or Diana, Walther, etc. will do pretty well in good conditions. I prefer a bigger, heavier pellet that has a higher BC as it will buck side winds better. Elevation adjustment is pretty easy. Gauging how the wind affects the pellet is harder because it's generally not consistent. I've shot good long range groups with a Beeman R1, R10, Webley Tomahawk in .25.
"but I'll be needin' that gun, fer squirrels and such."