A 2 Upper Rear Sight Tool Homemade

Most AR 15 assembly of the gun can be done without all the tools I call these tools bells and whistles. Purchasing such tools would be helpful if building a number of guns but not critical as long as you are careful if building one gun. I was able to assemble the lower and the upper at the kitchen table with the exception of having to make this tool. This did not include the gun barrel!  Brownells  has an excellent video on the process of assembling the A 2 sight . In vest the time to watch the step by step video.  If you have a helper you can do just as good a job without all the expensive tools Putting together the rear sight on the A 2 upper is not hard on the kitchen table. Automotive Bearing grease is good but Vaseline will do for holding the ball bearings in place. Use some folded up bath towels so you protect the gun and table. The hard part is compressing the spring and putting in the final pin.at the base of the sight. In looking for something to use as a tool I pulled out a Paper Mate pen. The back fit in the hole for the spring. The pen I used was Paper Mate Write Brothers Grip M. I used a hack saw and made a grove deep enough to compress the spring and checked it by looking down the pin hole. Another way to check for depth is to use a quarter as a measuring device cover  the words In God We Trust  and the G should be showing but if you are a little deeper it could not hurt, but at least at least that far.  Put a little masking tape around the hole in the upper in case the person driving the pin misses. Explain to the person driving the pin that, it is better to take a number of gentle taps rather than a denting the gun. Start the pin in the hole but not to far. Now get your helper ready to drive the pin. align the grove you made with the pen and compress the spring using your other hand to hold the upper.  Leave the cap on the pen and use a wash cloth to protect your hand and compress the spring and your helper will tap the pin into place when you say when to start. A three  inch 16 pinny steal nail is good for a punch grind the point off flat. Use the nail head against the pin hitting the end you flattened to hit with the hammer. This will make it less likely to have the punch slide off and dent the upper. With about 1/8 inch of the pin sticking out now use a smaller punch and finish the job yourself.
Richard W. Norman   Author of American Handbook on Guns Ammo and Freedom