I am seeing a lot of postings by first timers, so I thought I would put together a lessons learned list. They are in no particular order. You experienced guys feel free to add to the list.
The selector stop tab may try to disappear when removing the trigger guard rivets. So keep an eye on it.
Be sure to get the selector stop plate on with the tab pointing toward the selector side.
Check the side to side alignment of the gas piston with the gas port before riveting. Misalignment can be caused by an out of tolerance receiver or incorrectly placed rivet holes.
An underfolder won’t go together the first time, regardless of the order that you assemble the parts. Thats just the way it is. But for starters, the pin order is: the pin that gets hidden in the right side of the receiver, the pin in the nut, the pin that retains the pushbutton.
When disassembling the underfolder (because you didn’t get it together right the first time), the pushbutton will shoot across the room and hide when removing the retaining pin. Anyone have an extra push button they would like to sell?
Be sure to get the top cover fitted so that it goes all the way down in the back and the cover release button sticks all the way out. Otherwise, the cover may come flying off and hit you in the forehead when you fire the gun.
Make sure both of the hammer spring legs are resting on the trigger assembly. Otherwise the trigger wont reset reliably.
If your trigger hangs up at the very first of the travel, check for interference with the trigger guard rivet.
The trigger guard should point toward the pistol grip, not the mag well. Remember what a pain it is to get those 4 rivets out?
Believe it or not, pulling the barrel saves time. Even if you screw build.
Use antiseize on the barrel and barrel pin.
A chirping sound when drilling the rear trunnion rivets means the bit is about to break.
When adjusting the front sight. Imagine pointing the bore line at the target. Now move the sight toward the hole the bullet made.
You can remove the top handguard wood by rotating it 180 degrees on the gas tube.
An empty 22 cartridge can be used as a makeshift trigger pin sleeve. A large paperclip can be formed into a makeshift shepherds hook (pin retainer).
Krylon or Duplicolor, not Rustoleum.
That funny looking spring and the extra little parts are for the full auto fire control group. You do know that it is illegal to install these, right? Oh, the little hook shaped thing is your disconnector. Install it and the little coil spring in the trigger assembly. If you are going to reuse the original disconnnector, grind off the tab on the back of it first.
If a 223 (5.56) is loaded into a mag by mistake, it will chamber and fire, but not extract. It will look real funny when you get it out.
The muzzle break is supposed to be tilted and the gas piston is supposed to wobble.
The bolt carrier has to be removed before the top handguard can be removed.
A yugo (CFS) underfolder trunnion is 1.2mm more narrow than a standard trunnion. That is, it will need to be shimmed to fit a standard 1mm receiver.