OUTSTANDING LINK Jack! That lays it all out better than I could have written it myself. I've added that one to My Favorites. There's some great info there.
Fender, if you do go with a build, please feel free to hit me up with any questions you might have. I'm happy to help. Also be sure to post pics as you go. Good hunting.
Oh yeah, I almost forgot. A quick warning if you go looking for parts. Stay away from the hammer with the notch on the top, and the bolt carrier with the slot cut in the bottom. These to were first introduced by Colt in the original AR-15's, and are designed to tear it apart as it's fired. These parts really SUCK!
This is a drawing of the sucky hammer.
Note the notch in the top left. This produces two edges that catch and tear away at the bolt carrier and firing pin, with the crappy bolt carrier.
The 2 pics below show the 3 types of bolt carriers. In each, the crappy SP-1 type is on the top, (note the HUGE opening that exposes the underside of the firing pin), and the one you are looking for is in the middle. The one on the bottom is for the M-16, and has more material at the back end to trip the Auto Sear, in Auto or Burst Mode. That one can get you in trouble if you have it in your rifle.

This is the better hammer type. Note the rounded top corner of the hammer.
The newer Light Weight hammers are even better. Since there is less mass in the upper part, it moves faster creating a shorter hang time, that is the time from the release of the trigger to the time when the round leaves the muzzle.

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Slow is Fast, Fast is Slow
Violence may not be the best option, but it IS an option
