I think spqrzilla's point is that you CAN be prosecuted under Colorado law despite committing the "crime" outside Colorado. Colorado law enforcement can request arrest and extradition from authorities in other states -- that's pretty standard. The chances of Colorado going to those extremes over you selling or giving a high capacity magazine to a citizen of another state where said item is legal are probably pretty slim and you could always appeal for asylum but it's within the state's legal powers and the contention, "Colorado law, ends at the border though...WY,NE,KS,NM,UT,OK will not enforce CO law inside of their borders..." is patently false.