AR-15 Build Part 4

In B.O. Special, I introduced the newest addition to the gun cabinet and reviewed the rifle kit from Del-ton.
In Part 1, we talked about tools and preparation and installed the magazine catch.
In Part 2. we installed the trigger guard.
In Part 3, we installed the bolt catch.

This time, we’re going to install the pivot pin.

First I used a small drill bit to make sure there were no burrs inside the spring/detent hole on the right side of the receiver. It was clear.

Then put receiver in the hobby vise again, only this time with the front of the receiver up.

Then the pivot pin detent spring drops into the spring/detent well.

The detent goes on top of the spring. The spring is long enough that the detent sits on top of it outside the well and will just fall of you let go of it. The spring has to be compressed and the detent pushed into the hole while installing the pivot pin.

I have read that this is the most difficult part of assembly if you try to do it without the special pivot pin installation tool. This is where I “invented” a new procedure that made installing the pivot pin a snap.

I noticed that, as the pivot pin is inserted into the holes on the mounting ears on the front of the receiver, there is a gap between the pin body and the top of the spring/detent well.

I surmised that a thin, flat piece of metal, stiff enough to hold the detent down, but thin enough to fit into that gap would enable me to install the pivot pin easily.

I then occurred to me that feeler gauges are stiff but thin pieces of metal…and they come in a selection of sizes…surely one of them would fit the bill. After a little experimentation, I decided that a .014″ feeler gauge was the right size for fitting in the gap, but allowing the pivot pin to be installed easily.

I pushed the detent down into the well as far as I could with my needle nose pliers, then used the feeler gauge to push it the rest of the way down and hold it in place against the spring tension.

Then just slid the pivot pin into the holes in the mounting ears over top of the feeler gauge.

Once the pin was in as far as it would go with the feeler gauge in place, I just pulled the gauge out…

…and rotated the pin so that the detent popped into the groove.

No muss, no fuss and no special tools required.

And there you have it.

Next time we’ll install the trigger assembly.

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