there are five public ranges that I know of that go out past 400 yards here.

CRC in byers, NRAWC in raton, DOW range in Buena vista, PWSA in pueblo, and pawnee nat. grasslands.

theres sadly not much else long range around this area that's public.

I'm lucky enough to have a buddy that lives on some land in sedalia that I can shoot on (out to about 450), but thats not exactly open to the public. From my experience, if you want to do much long range shooting, youre pretty much stuck driving far one way or the other.