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It's been many years since I built an upper and I'd forgotten that the part I hated the most - on the entire rifle - is installing the ejection port cover. I've lost a bit of dexterity and steadiness in my dominant hand since then due to a nerve pinch which made the job almost impossible at first. I almost gave up and bought a Magpul or Strike Industries newfangled version that installs pretty easy, but really didn't want to go the polymer or billet aluminum route. Through trial and error I finally figured out a way that even makes a standard cover install a breeze. Warning: No pictures as I'm not taking any of the durned things apart and they really aren't needed as you re really just using a short 1/8" rod to help out.
This assumes you have the lower, ejection port cover, spring, and hinge rod with the c clip thingy already attached. This is easiest if the upper is held captive in a vise block, but can be done without.
The cliff notes version if you have done this before: Do everything as you usually do, but insert a short length of 1/8" rod or drill bit through the rear port cover hole and a short ways into the cover itself to keep everything held together as you finesse the spring into shape and run the hinge rod through it until you get through the hinge pin hole at the rear of the ejection port.
The version for them that haven't installed one before and don't want to wimp out and put in a plastic one:
This assumes you have the lower, ejection port cover, spring, and hinge rod with the c clip thingy already attached. This is easiest if the upper is held captive in a vise block, but can be done without.
The cliff notes version if you have done this before: Do everything as you usually do, but insert a short length of 1/8" rod or drill bit through the rear port cover hole and a short ways into the cover itself to keep everything held together as you finesse the spring into shape and run the hinge rod through it until you get through the hinge pin hole at the rear of the ejection port.
The version for them that haven't installed one before and don't want to wimp out and put in a plastic one:
- Dry fit everything except the spring. If the cover is bent then unbend it.
- Lubricate the hinge rod and spring.
- Feed the hinge rod in from the muzzle end through the dust cover. Stop just before the spring opening
- Use a short section of 1/8" rod, or in my case a broken 1/8" drill bit to hold the left side of the cover captive to the upper. This is the magic part, because it keeps everything alignedd and prevents the tensioned spring from unwinding at the last moment..
- The spring has long and short tails. The short tail goes on the left and points up, Hold the spring in your left hand with the short tail pointing up then with your right hand wind the long tail clockwise until it points down to pre load the spring.
- Carefully insert the left/short tail of the spring into position holding it down with your left thumb and then feed the right side in place resting the long spring tail in the obvious crease in the cover. At this point your left thumb is keeping the spring in place.
- Slide the hinge rod through the spring and continue until it is just touching the 1/8" guide rod you fed in step 4 above
- Your left hand is no longer needed to hold everything in place, so use it to make sure the guide rod does not come out prematurely
- Push the hinge rod through the rest of the dust cover being careful to slide it into position in the upper as it pushes the guide rod out of the way.
