Looks like a good list.
Notice that a couple of guys hit on a good point.....most problems are likely to involve the bolt and or bolt carrier and if in a hurry just swap out the whole thing and look to fix the problem later.
Both in the Infantry and Artillery I found that troops most often lost the firing pin retaining pin followed by the extractor pin and extractor spring.
This was usually in the field but sometimes even in barracks. Nothing like finding a firing pin retaining pin in a crack in the floor and having to go through two platoons worth of M-16A1 rifles to find out who lost it and what they did to get it past the Armorer.
Of course the best replacement part is a complete rifle.
You asked what I have seen broken on and AR type rifle so.....
Flash hider (old three prong) also bird cage lost.
Gas block /front sight loose, canted, bent, or broken
Handgaurds cracked left and right
DUst cover latch missing
Dust cover spring broken
Dust cove,r pin, and spring missing (not sure how he managed that)
Upper bent and or cracked on the carrying handle/ rear sight area damaging rear sight
Lower cracked at the rear where the buffer tube screws in.
Buffer tube cracked or broken completely though
rear take down pin plunger and spring missing as result of above
Rear takedown pin missing see above two
Drain screw in Butt missing resulting in or threatening last two above and loss of stock
Butt stock chipped, burned, or hard butt plate and associated butt trap door cracked or missng
Grip screw and grip missing and selector spring and plunger and selector unreliable as a result and indanger off being lost during field dissassembly
Lower cracked at front take down hinge
besides loss of extractor and associated parts , broken extractor (Sometimes binds action well and truely good)
Cracked and shattered bolts ( on well used M-16A1s)
Barrel bent noticably
It may be possible I have seen a few more M-16A1 rifles and been responsible for small units issue of such than most folks so do not be alarmed but I saw and delt with all of the above in my first three year hitch and some again later.
Hopefully you will avoid all this long list by not being a sloppy soldier, staying out of places you might get shot at, and not firing a bazillion rounds of ball, tracer, and even more blanks in all sorts of weather while using a rifle perhaps ill treated by five to twelve previous "owners", but you did ask what we have personally seen break on an AR.
My infantry squad carried basically all the parts you mentioned in our "squad can," an ammo can that held parts, additional cleaning gear, a couple of spare magazines, boot polish & brush, a spare razor or three, cammo sticks, and a hand mirror. The can was heavy and non ergonomic and had square corners that always seemed to find a tender body part to bash so it was good not to be on the Squad leaders Poor Performing Private List. Those parts you mentioned (and yes we carried multiple firing pins retaining pins, extractor pins and springs) came in very handy at times.
Sorry if this list upsets the AR-philes, but "this is true, I saw it myself, I was there" really is true this time.
-Bob Hollingsworth
