Most bolts for an AR-15 come fully assembled, but if yours isn’t, this is how you assemble one from parts. I like to start by lubricating all the pins with some light gun oil. This will make them easier to install.
Also, be sure to add a bit of grease to each of the springs.
Place the extractor spring into the spring recess in the bolt with the large end inside the recess.
Now place the extractor on the bolt
and clamp it into place using a padded machinist vise.
Place the roll pin in the starter punch and begin driving to pin through the bolt,
switching to a roll pin punch to drive it the rest of the way.
Insert the ejector spring into the recess on the bolt face.
Align the clearance cut on the ejector with the ejector pin hole and insert the ejector into the bolt.
Press the ejector end with a flat face punch.
Once the clearance cut is in line with the ejector pin hole, insert a small punch to capture the ejector.
Now take the roll pin starter punch and seat the roll pin.
Use a roll pin punch to finish seating the ejector roll pin. As you drive in the roll pin, you should drive out the small punch you used to capture the objective.
Now slip the ring into the groove. Repeat this process with the remaining two gas rings.
Then adjust their positions so the open ends are not aligned, thus not compromising the gas seal.
–Larry Potterfield