I also live in Northern Colorado, and to me, a trip out to the Pawnee Grasslands for a day of shooting is like a Caribean vacation for most folks. There are certainly more restrictions on shooting than there were ten years ago, but there are still a lot of acres to share. Since I work rotating shifts, I have days off mid week when there are not a lot of others out there. Go early and/or stay late and enjoy the sunrises and sunsets. The sounds of the coyotes, watch the pronghorns and jack rabbits run full out accross the prarrie. There are some places where shooting is prohibited, often because people have made such a huge mess of the area and left behind everything from TV sets and freezers,to old vehicles. It takes years for the area to recover once its cleaned up. I have never been accused of being a radical enviromentalist, but I enjoy the out of doors and don't want to screw it up.
It is required that you only use paper, cardboard, clay pigeons, or real steel target systems that you take with you when you leave. I would agree that the Rangers we meet out there today are more likely to be the fresh out of college "Greenie" than the guy who would stop and talk to you about guns for 30 minutes, but be respectful, careful, and pick up after yourself. As with any contact with law enforcement, be cooperative, don't argue, and if you feel they are unreasonable, get their name, badge number, vehicle number, document the date, time, and location, and take it up with the District Manager at the office in Fort Collins. Simply put, dont act like a raving lunatic and dont be a slob, and you will be fine.
I always take trash bags with me, not only to pick up my own mess, but put a little effort into picking up things others have left behind. When I'm shooting from one position, I'll lay a tarp down, to make it easy to pick up the brass, yes even the 22s. If I'm doing "run and gun" stuff, I will walk the path I traveled and try to get as much brass as I can find. Once again, not just my own, anyones. One day I was out shooting and an old retired guy came along just picking up brass that was left laying around. He said it brought in a little spending cash, and gave him a reason to get out of the house. Not a bad idea, and one I will keep in mind when I retire.
We have enough anti shooting forces against us, lets not add to it by being slobs and giving them a legitamate complaint about leaving a mess everywhere we go. And yes, leave the pyrotecnics at home, if you have ever seen how fast a wildfire can move accross a prarrie, you understand why.