This is my first AR-15. It's from the Smith and Wesson M&P Line, specifically, their model "R" chambered in 5.45X39. This rifle looks completely different from when I started it. I changed out the grip from the standard A-2, to an "Ergo" grip. I also swapped out the handguard to a Magpul Carbine length set with 2 rails; one for a foregrip and a Knights Armament Corporation Flashlight holder holding the Surefire G2 light and the other holding on the Magpul foregrip. The Flashlight is set up so that my left hand thumb hits the back of the light for instant on/off illumination. I also tossed on the LMT SOPMOD Stock which I vastly prefer to the standard M-4 stock. This is a very light shooting rifle. Barrel twist is 1:8 with a 16 inch barrel.