I have been out for a long time,( '80-'86) but the M16A1 I was issued was a colt. Now I was in the Engineers (25th Infantry) and we always had the rifle slung over our backs while we constructed anything, the thing was constantly falling to the ground (unloaded of course), but it was pretty durable. We moved around in 5 ton dump trucks with jump seats, dropped it a few time from there to. I remember the hand guards broke a lot, and the front sight blades bent, the unit armor was always pissed off (REMF).
In basic, remember the move when you run and hit the prone position. Drop to your knees, dig the butt of the rifle in the ground to break fall, roll left or right and shoulder the weapon, that my have not been enough to break the thing. . Now, for some reason I do not remember the bayonet training. Fiberglass and plastic baby, nothing like solid wood. They should make them out of carbon fiber now.