The casing/shell deflector (triangular protrusion just behind the ejection port -- can be seen in both of the images above) is used to prevent the ejected casings from hitting left-handed shooters in the face. Left-handed upper receivers are available but cost a bit more than standard right-...
The original rifles had triangular-shaped handguards, no forward assist, and no brass deflectors. The early guns had some problems, due mainly to using the wrong powder. Complicating things was that the rifles were touted as being "self cleaning" and were not issued with any cleaning kits. ...
The AR-15 made use of high-impact fibrite stocks, pistol grips and handguards. A selector lever on the left side of the rifle could be manipulated with the shooter’s right thumb without removing the hand from the pistol grip. The magazine release, on the right side of the receiver, c...