IMHO,
I have heard that Bighorn has reopened under a new owner, but have not been there to check it out.
Matt,
If you drive through Boulder on 36, headed towards Lyons, about 5 miles north of Boulder the highway divides and a left-hand turn takes you into Left Hand Canyon. There is a well-known resturaunt at the intersection, the Green Briar. Head up Left Hand Canyon about 2 miles or so. There is a pull off on the right. You can walk in 25 yards or so and then there is a box canyon about 100 yards long where people shoot. You can tell from all the ammo casings. It is often pretty trashed out from people shooting fruit and vegetables, computer parts, and God knows what else.
I went up there today and did some shooting, and found the place in pretty good shape. Only other people there was a couple shooting trap. Then the guy surprised me by pulling out a full-auto Mac-10 and a full-auto Uzi. He was showing his girlfriend how to shoot them. Judging by the way she looked at him and kept grabbing him, I'd say a full-auto weapon is THE way to pick up and impress women. [;)]