Start by pulling the fire control group out of the lower receiver.

You may have a blow primer piece hiding under the trigger and the only way your going to get at it is to remove the trigger. Plus with the lower sitting around for a while, the old fouling in it may have dried caked up between the pins and channels, and the FCG needs to be pulled anyways to give it a good cleaning.


To pull the FCG, lower receiver in hand only, put thumb pressure on the ejection side of the selector shaft, then switch the selector from safe to fire and back to walk the selector detent pin out of the selector groove to allow the selector to be removed (the detent pin will not fly out of the channel for it.  If you can't get the selector out this way, then remove the pistol grip, and make sure not to loose the selector detent that will be up in the channel, and the spring in the grip channel.



Now with the selector out, hold the hammer at the un-cocked position so it does not twist sideways as you drive the hammer pin out, and drive the hammer pin out with a punch.  The hammer has a center J spring so depending which way you drive thehammer pin out (it has a center groove, and only one side groove), may have only initial hard spot to get the pin to start to drift out, or a second hard spot as the side groove has to get past the J spring as well.  With hammer out, the trigger pin will  now just push out and you can remove the trigger and disco as well.



Now check the bottom of the receiver void cavity for any debris, and give it a quick CLP cleaning.

With the FCG parts in hand, give them a good CLP cleaning, then check the parts out for any burs that my need to be cleaned as well.


Parts cleaned and debur'd, make sure to CLP lube the parts on the wetter side ,and the receiver pin channels, and put the FCG back in.

The disco spring gets installed large coils side down into the trigger tail slot, and the parts will install in the reverse order you pulled them out.  As for the pins, does not really matter which side you put the single side groove, since only one of the hammer spring legs locks into the side groove on the trigger pin to hold it in place.




And the guide to build a lower receiver, since when you have the FCG out, it's a good time to pull the mag catch by pushing the catch button all the way in with a pencil (blow flush of the receiver) and unscrewing it from the button on the other side of the receiver to clean the mag catch and channel as well.
Note, when you reinstall the mag catch, the end of the threaded shaft should be flush with the face of the release button. If you find that the end of the shaft is either high by a half wind, or low by a hand wind, then un-thread the catch, and rotate the button around in the receiver channel a half turn instead.
http://www.ar15.com/content/guides/assembly/lower/

Lastly, when the FCG is back in, make sure that the side of the selector U slot for the fire position is not binding on the sides of the trigger tail.  If it binding, then either the selector is out of spec, or you don't have the selector in correctly so the selector detent is in the groove.

I would leave the springs alone, and replace them when they either get too weak or snap, to warrant a spring replacement instead.