I have two post-ban ARs and am thinking about getting a preban now and have run across a nice one at a local shop. Its a new  in box Colt AR-15 A2 HBAR R6600. Its a unblocked green lable  with fenced mag  release but the guy says its a transition model so it doesnt  have a lug. What is a fair price for this rifle? Is there  any price difference between one that has a fenced mag  release and one that doesnt? How much extra  can I expect to pay  for one with a lug.What should I be  on the lookout for as things that I should want my pre-ban to have? This rifle will be a shooter  but I want  something that is going to go up in price over the years! Thanks alot  for any help you can give!

BKVic