Did you end up going out on the 19th? I've held 4 group shoots out south of Tarryall off of Turner Gulch Road (CR23) this summer with ARFCOM and Snipershide members. You can shoot out to 1k there and there is already a fire ring set up. It's right off the road but difficult to see from the road, making it relatively isolated and not heavily used even in the peak of camping during the summer.

CMS