This is a K1A1 Paratrooper side charging semi auto by Daewoo. This is the South Korean answer to NATO's requirement for rifles that run STANAG mags. This is chambered in 5.56x45. It runs most any STANAG mag. GI mags, PMAGS, Thermolds. I have run all of those plus a 100 round Surefire through it with no problems. 16 inch barrel, direct impingement operating system. Takes AR grips and some small parts. I think triggers, bolts and firing pins are the same. Bolt carrier is proprietary and you can see why. There is no buffer tube, that is how it can run the cool wire collapsible stock. I bought this unfired in 2011. I have put maybe 400 rounds through it since I bought it. It still had shipping grease/cosmoline all inside it when I first got it. I believe I have the original box too. It is a fantastic handling little rifle. The built in flash hider works very well and it is about as light of a rifle as you can get in an AR platform. The railed forend is a very hard to obtain DI Optical rail from the South Korean company that makes them. I have never seen one for sale with this rail on it. Most folks run the Stormwerks rail and I prefer the looks of this DI Optical rail. More info here: http://diopticalusa.com/?page_id=1125 Factory front handguard included. Pictures: Bolt and recoil spring setup: Please contact me via PM with any questions. I am located in Issaquah, WA. Sale to be completed at a gun shop that is reasonable for both of us to get to so we can satisfy i594. You'd be surprised how far I am willing to go to facilitate this sale, so ping me if you aren't in the immediate Seattle area, I am more than likely willing to come half way at least. I have family in Portland, OR so we can figure out a way to do a legal transaction if you are from Oregon and interested as well because I always am looking for a reason to come down to Portland to visit family. $1750 cash and I'll throw in the sling, LaRue handstop and a couple beat up GI mags. These go from $1700 to $2000 on Gunbroker if they are ever there and that is without the really hard to find and obtain rail.