Seekers,

Use this checklist first and see of it helps solve your rifle's problems.
GENERAL MAINTENANCE CHECK
for AR 15 rifles

---EXTERIOR EXAMINATION
-Unload the rifle and verify clear.
-Check the rifle for any damage from being dropped. Check the muzzle, front and rear sights, handguards, barrel, buttstock and sight alignment.
-Ensure that the upper buttstock screw drain hole is clear.
-Check steel parts for rust and porosity.
-Check for any parts that may be loose on the rifle. Check the pistol grip, buttstock, front sight assembly, barrel, and the flash suppressor.
-Pull charging handle back to check carrier for any binding or roughness.
-Check the bolt catch tension and range of motion; depress bottom of bolt catch and retract carrier, check for binding of carrier on the bolt catch.
-Check the magazine catch tension and range of motion. The magazine catch latch should sit flush in its slot and its threaded end should be flush with the surface of the magazine catch button.
-Check that the ejection port cover functions in the open and closed positions. Make sure that the “C” clip is on the ejection port cover pin and that the ejection port cover spring is properly installed.
-Operate safety and check for proper function, tension and range of motion.
-Check trigger pull and disconnector engagement, perform the “function check”.
-Check that charging handle locks into upper receiver easily.
-Check that the “paddle” of the bolt catch is not hitting the outside of the upper receiver.
-Ensure that the gas tube roll pin is present.
-With the bolt out of battery ensure that the forward assist closes the bolt fully.

---INSPECTION OF UPPER
-Pivot upper open/ “shotgun”, you should feel the buffer pushing against the carrier when you do this, check the takedown pin for ease of movement and fit.
-Check that the bolt carrier moves easily from the locked position to the recoil position by moving it with your finger, not with the charging handle.
-Check to make sure that the rear of the carrier is flush with the end of the upper receiver when the carrier is fully forward.
-Separate the upper and lower receivers. Make sure the pivot pin moves easily and is secure.
-Remove the bolt carrier and the charging handle.
-Ensure that the auto sear clearance cut is present.
-On A2 sights make sure that the drain hole under the elevation wheel lock screw is clear.
-Ensure that the takedown pin lug has the proper bevels and facets and that the pinhole is chamfered and oblong.
-Check the charging handle for damage and straightness, check for damage to the upper where the charging handle locks in place.
-Clean and inspect the bore, look for excessive wear, rings, scratches, or other damage. Look for evidence of chrome plating around the muzzle and chamber.
-Check the crown of the barrel for burrs and wear.
-Check the end of the gas tube for excessive wear or damage.
-Inspect the inside of the upper for damage, such as cracks or wear around the cam pin clearance cut.
-Check the gap between the receiver and the barrel extension, it should be no more than 0.012”.
-Inspect the feed ramps for smoothness and completeness.
-On A2 sights make sure that the rear sight base hits the receiver on the last whole click of the elevation wheel. The 3/8 or 3/6 must be aligned with the index mark on the receiver.
-On A2 sights, run the rear sight base to its highest elevation, ensure that it does not rock back or twist more that it does in its lowest position.

---INSPECTION OF BOLT CARRIER
-Check key: make sure that the key is tight, the screws are tight and staked in, and front of the key is not damaged. Use a wrench to make sure the heads of the screws are not snapped off.
-Operate the bolt to make sure it moves smoothly in the carrier.
-Remove the firing pin retaining pin, the firing pin, and the cam pin, with the bolt in the unlocked position stand the bolt carrier on end. The bolt should not slip into the bolt carrier.
-Remove and inspect the bolt, inspect the locking lugs for damage or excessive wear, ensure that the cam pinhole is swaged.
-Check the firing pin retaining pin for damage and straightness. If the firing pin retaining pin is bent, then the hammer may be dragging on the firing pin.
-Check the cam pin, firing pin, and the gas rings for damage and wear.
-Check the firing pin protrusion. Use a gauge or calibrated eyeball.
-Depress the ejector to check its tension and to make sure the ejector goes flush with or below the bolt face.
-Check the extractor’s tension and range of motion using a cartridge case. Check it in both the locked and unlocked positions in the bolt carrier.
-Remove the extractor.  Check the pin and hook for damage, and check the spring and bumper.
-Check to make sure that the gas tube does not bind in the carrier key and for proper gas tube alignment.
-Clean and inspect the chamber, look for scratches, rings or other damage.
-Reassemble the bolt carrier, make sure that the head of the firing pin retaining pin is flush or below the surface of the bolt carrier.
-Slide the carrier and charging handle back into the upper receiver, lock the charging handle in place and hold the bolt carrier to the rear.
-With the upper at a 40 degree angle to the ground release the bolt carrier and check that it locks fully into the barrel extension under its own weight.
-Check the head space.
---INSPECTION OF LOWER
-Trigger guard should not protrude into the magazine well.
-Insert a magazine into the magazine well and ensure that it drops free.
-Check the pivot pin, and takedown pin for wear and fit, they should be snug but slide easily.
-Check disconnector engagement: with the trigger forward, rotate the hammer to just short of the cocked position, the tip of the disconnector should almost touch the middle hammer hook. Holding the trigger to the rear, cock the hammer and release the trigger, the trigger should catch the hammer, and the hammer should smoothly slide out from under the disconnector hook.
-At no time allow the hammer to strike the lower receiver or the bolt catch.
-Remove the hammer and check the hammer spring for proper placement and tension. Inspect the middle hammer hook; lower hammer hook and the  “J” spring for damage. Ensure that the “J” spring is staked.
-Remove the trigger and disconnector. Check that trigger spring is properly installed and that a disconnector spring is present.
-Check the hook of the disconnector for damage.
-Inspect the trigger, check trigger spring tension, disconnector spring, and wear or damage on the sear face of trigger.
-Ensure that the disconnector slides easily in the trigger slot.
-Check the inside of the lower for foreign matter, such as a primer in the pistol grip hole.
-Remove the buffer and spring and inspect them for damage; such as small indents in the face of the buffer caused by the buffer retaining pin. Check the buffer spring for proper length; 11 ¾”-13 ½” for rifles 10 1/16”-11 ¼” for carbines.
-Check the buffer retaining pin for function and range of motion.
-Check the buttstock screws and lower receiver extension for tightness.
-Reinstall the buffer and spring.
-Reinstall the trigger, disconnector and hammer.
-When installing the hammer make sure the hammer spring legs are on top of the trigger pin and in the cut outs or the trigger pin will fall out. The wide end of the disconnector spring goes into the hole in the trigger.

-Reassemble the upper and lower receivers.
-Check to make sure that the charging handle does not drag on the “bridge” of the lower receiver.
-Look into the magazine well to ensure that the upper receiver does not overhang the magazine well.
-Insert an empty magazine and check for fit and function of magazine catch and bolt stop. The magazine should release smoothly and insert without undue force.

---THE RIFLE IS READY TO BE TEST FIRED---

[edited when the link broke]

I got a blank black screen.  I thought maybe it was black print on a black background.

As the bumper sticker says,

"Sometimes you must believe before you can see"

and apparently I am an infidel because I can't see anything either.

It is a really cool black screen.

Use the Force, Luke.

No more black screen. :D