I'm building a new upper.  I have the stripped upper receiver, bolt and carrier, FF tube, and charging handle, and now I just need a barrel right?  One with gas tube and A2 sight tower.
Thanks for any advice.

Not to be a smartass or anything...

...but you know that oddly-angled hole on the right side of your stripped A2 receiver?  A Forward Assist Assembly needs to go into it.  Thats the Forward Assist Button, the Pawl, AND the spring, held in by a roll pin.

And, unless you're choosing to forego the ejection port cover, you're gonna need one of those, the cover hinge (which is little more than a rod with a notch cut around one end), an e-clip to hold the hinge in place, and the spring.

And how about the A-2 sight assembly?  THAT's a major PITA...but let me tell you why...


First off, when you FIRST assemble the sight from the parts, you realize that the elevation adjustment wheel is actually TWO parts, the upper part and the lower part.  IIRC it is the upper part that has the numbers.

There are a lot of small parts here.  Such as the ball bearings and the little bitty allen screw with, as mine came, a tiny dot of some substance designed to keep the screw from coming loose.  I won't call it loctite because it looked more like wax or greasepaint.

The M16A2 tech manual has detailed instructions as to how to properly assemble and calibrate the A2 rear sight.  I can't do it from memory...I only remember the steps sort of...it's been a year since I last build up a receiver from scratch.

I DID, however, change out a bad A2 upper to a decent Eagle Arms A2 stripped upper, so I know about the stuff that needs to be done.  First I pulled the barrel.  Then I pulled the ejection port cover assembly.  Then I drove the roll pin out of the receiver that secured the A2 sight assembly.  Then I removed the sight assembly.  Then I spent 20 minutes finding the damn ball bearings I dropped.  Then I drove out the roll pin holding in the Forward Assist and removed it.


Voila...ruined stripped upper.  Shitcanned.

Put new forward assist into new stripped upper.  Using plastic hammer, pounded roll pin carefully back into place from the bottom just in case.

Since the A2 sight was already calibrated, I didn't dick with it.  Just put the ball bearing on the spring and slipped the elevation wheel back into place.  Then carefully stuck the other ball bearing on the other spring and gingerly re-inserted the rear sight assembly into the hole, tightening it down with the elevation knob.  Once it was deep enough, and all the parts remained intact and the slot lined up, I inserted the roll pin and again, pounded it in place gently with a plastic hammer.

The simplest, yet largest PITA for me was the ejection port door.  First, place ejection port door in place in the "open" position.  Insert hinge pin to gap in door where spring goes.  Fight with spring for a half hour.  Drink beer to calm nerves.  Fight with spring some more.  Finally get spring inserted properly with hinge pin through it.  Get bumped.  Watch spring come undone from how it's supposed to go.  Cuss.  Drink more beer.  Repeat until you've gotten it right, sliding the hinge pin all the way through to the other side.  No, there is no E-clip at that end.  Only at the barrel end.  Want to know why?  So the rod won't come out with only one E-clip because the delta ring assembly prevents it form coming out this way when the barrel's on.


Voila, instant "assembled" upper receiver.  The Charging Handle and Bolt Carrier Assembly I didn't even dick with.  Just pulled 'em both from the old one and moved 'em to the new.  Since I was using the same barrel, headspacing wasn't an issue.

Re-barreled the reciever with (I KID YOU NOT) just the armorer's barrel wrench and the same plastic hammer.  No vise.  No vise blocks.  I do NOT recommend this procedure.  It worked for me but by the grace of God.  I don't know the actual ft/lbs., but it was 3/4 of a hole past snug, and I was smart this time and lubricated the receiver threads with CLP before tightening on the barrel nut.  How did I get it from snug (not lined up) to 3/4 of a hole past the snug point?  By applying the plastic hammer to the barrel wrench while it sat on my lap.  Yes, I'm a soup sandwich.  But it worked.

Again, by the grace of God, the thing lined up and I inserted the gas tube.  Then got the gas tube into the sight tower of the barrel.  GINGERLY inserted gas tube roll pin and used the tip of a small finishing nail to drive it into place.  Again, I do NOT recommend this tool, but that's what I used.  I'm not that bright.

The delta ring assembly was still attached to the barrel...thank goodness.

Put my handguards back on, and mechanical zeroed my rifle.  I haven't taken it to the range yet to BSZ it but I will the moment I have the time.  Rifle function checks okay, with no rubbing or binding.

Panz
[bounce]

Don't forget the handguards and flash suppressor. You'll need some sort of washer for the FS too.

pongoAR;  I suggest getting a technical manuel either from the downloads section on this site or buy one.  It will be a great help in asenmbeling the upper.  If its a flat top upper you don't have to mess with the rear sites as they should be on the carrying handle, if you get one.  If not a flat top don't forget about all the parts associated with the rear sights.  Also, as stated in earlier posts, parts for the ejection port cover and forward assist.  Also the right size  gas tube for the length of barrel you have.  Get the tech manuel; it will help.

..and the gas tube roll pin.

I guess I wasn't in depth enough when I asked for help.  I realize I need a fwd assist, and a dust cover.  The barrel ASSEMBLY I'm getting contains a front sight, and seeing I'm using a flattop, I am putting a Arms #40, so the rear sight issue is mute.  Thanks for the advice everyone.