Re: Can someone from Colorado tell me how it works...
There is no BLM land between Durango and Silverton off of 550.
That area is extremely mountainous. Not much of a chance for open shooting off of 550. The "million dollar highway" as it is called gets lots of traffic. Also, lots of private land near the roads given the attraction to the area.
There are some 4WD roads that head west of 550 between those two towns, but again, mountainous. Yea if you dug hard you could probably find something.
If you go the other way, south, things open up some, so you might find some more accessible areas, but the northern third of NM is all private land, so be careful where you go south of the CO border.
You gotta remember - that is a relatively densely populated, highly recreated area. Yea you could head up towards Engineer Pass or Cinnamon Pass with a 4WD and find some open areas to shoot as you get above timberline, but there are A LOT of people up there in the summer - 4WD, dirt bikes, mountain bikes, hikers, lookie-loos - so you gotta be careful.
Id' start here, get some maps, and try to find a safe place to pop some caps:
http://www.fs.usda.gov/sanjuan/