Let me start off by saying this is my first AR so I’m not real familiar with all the lingo or abbreviations. This is not the piston-operated AR like I thought. This one has the gas impingement system (GI). The description of the gun was a lil vague at the time. It’s my fault though; I guess should’ve researched it a bit more before purchasing (live and learn). As far as shipping goes I ordered it on 10-2-12 and received it on 10-11-12, but I did choose the cash option so Buds had to wait on my cashier’s check to clear before they would ship it so 9 days wasn’t that bad. Enough of that bs. Now about the gun, can’t say enough good things. It shoots great, 300 rounds with no issues, extremely accurate, light recoil and breaks down super easy (no tools needed). The only thing I don’t like so far is the magpul stock. The padding is virtually nonexistent and it tends to cut into you, so I went and purchased me a LIMBSAVER recoil pad to solve that lil problem. As far as my recomemndation, I would recomend this AR to any one.... Its freaking awesome!