My first thought is F**K EM.
However, I pose a Hypothetical question.
How could either a WY or CO LEO be justified to make an arrest for a mag limit violation if someone were purchasing mags in WY and driving back across state lines?
Here's the way I see it, certainly open to interpretation.
WY has no obligation to enforce or jurisdiction over CO law and there is no WY law being broken. (I seriously doubt any WY LE would cooperate with any CO "sting.")
CO has no jurisdiction inside WY so any "stake out" there would be illegal IMHO. Hence, any search (you know you don't consent to searches right?) is illegal. I suppose if you were within sight of the state line, purchasing out of doors, you could be observed by an LE sitting in CO, but that's unlikely to occur.
Discuss.