Teardown Tuesday: AR-15 Lower Build

Ok, so it's not a real teardown. If you want a teardown read from the bottom up.  ;-)Parts.This shows the rough relation between the hammer and trigger. The hammer's notch gets hung up on the trigger's sear to keep it from snapping up and hitting the firing pin.More parts...First up -- and this wound up being the hardest part of the assembly -- is the bolt catch.The magazine catch was too easy. Nothing up a spring and screwing on a button. Meh.The keen-eyed will spot to the machining I did.There was a burr on the trigger that was proud maybe 10 mil -- 10 thousandths of an inch. I took a diamond file to it to smooth it out. Nothing to worry about -- and nothing to try to force into the gun either!The top picture shows the relation between the trigger and secondary sear and the spring that tensions it. What happens is the hammer gets caught on the secondary sear on it's way back as the action is cycling and it gets held by the secondary sear until the trigger is released. (I.e., one pull of the trigger give you one shot fired)It all goes in with a pin through both of them:Next: the hammer.The pin for the hammer is interchangeable with the trigger pin.Actually, a cool point is that the leg of the hammer spring falls into one the the hammer spring pin grooves to retain it. Inside the hammer there's a tensioned wire that falls into the hammer pin center groove to retain its pin.Next up is the safety. The safety detent spring is head in place by the grip so they all go in together.No problem.The last part I can mount without a buffer or butt-stock is the front takedown pin.The spring goes into the hole, pushes the plunger into the slot cut in the takedown pin and and falls into the detents. No problem.Parts for later:Here's the rear takedown pin along with it's spring and plunger just like it's brother up front. Also here is the buffer retainer and it's spring. Parts for when I get those in.Done:Simple. Took me 20 minutes when going slow. It was almost disappointingly quick.Teardown is opposite of assembly.(Note, that I had to do a crapload of machining on the magazine well that I talked about a few days back)