Outside of your AR-15 just blowing up, melting, or being futuristically atomized via circa 1960’s star trek phasers, there are essentially three systems that can keep your thunder stick from going boom. And in under half a minute, you can check these systems to ensure you stay in the fight. Firing system, gas system and recoil system (don’t really care if that is what they are actually called because in my head, that’s how the world works) all function together to ensure that rounds going down range always travel with company.
Take a minute to grab your AR-15 and then 30 seconds to check the following (this article addresses specific points that pertain to “direct impingement” style AR’s, keep your eyes peeled for a follow-up article custom tailored to piston AR’s):
(I know I listed it last, but for those of you with last names that start with the letters V-Z, wasn’t it great when the teacher would randomly start at the end of roll?):
1. Grab your buffer tube and try to twist it. Most people would notice a buttstock sticking out at a right angle from their AR, but for the brethren and sistren out there who have chosen the pistol configuration and have no stock, a buffer tube that is slowly walking its way out of the gun is not always immediately apparent. The problem with a loose tube is that if it backs out far enough, the next time your rifle fires the buffer retainer pin can eject into the cavity of the BCG causing immediate failure and making disassembly extremely difficult.
2. Check your buffer retainer pin. The little stud on the end of this pin ensures that the buffer doesn’t over travel and end up outside of the buffer tube. If the stud snaps off, it can end up literally anywhere in the rifle and cause any number of failures. A worn down stud can result in over travel as well, impeding the breakdown of the rifle making servicing in the field a pain.
3. Press in on the buffer. You should feel immediate resistance. If there is any slop (being able to press in the buffer even a short distance before resistance is felt) odds are you have a broken spring. It can result in the bolt not fully seating in the forward and locked position or even leave the carrier group stuck in the buffer tube itself.
1. Carrier gas key. Remove the bolt carrier group and try to wiggle the gas key. If it shifts at all, redirected gasses could result in failures to eject, leaving you with a bolt action/walking stick/club-thingy. Generally not good.
2. Gas tube. Stick your pinky up into the keyway, now try to wiggle the end of the gas tube that is sticking into the upper. A little bit of movement is normal as it literally floats free except for at the gas block. If it rattles around, your gas block may be loose. Running a gun until it cherries out may make for a lot of likes on Facebook and Youtube, but each component expands and then contracts at differing rates leaving plenty of opportunity for set screws to back out and spring pins to fall out
3. Cam pin hole. Ensure that no foreign material is present and that the bolt moves forward and back without too much resistance. If the cam pin cannot travel fully in its slot it can result in the gun not firing (debris trapped behind) or your bolt becoming a permanent fixture in your star chamber (debris trapped in front).
1. Firing pin retainer pin. Since the BCG is already in your hand might as well check that the firing pin is properly retained. Lightly slam the back end of the carrier into your palm. If nothing happens aside from a sore palm you passed the test, but you should probably do something about your weak palms. If the firing pin ends up in your hand, you need to replace the cotter pin that was supposed to be holding it in place. Next push the bolt face backward and press forward on the firing pin; you should see the tip of the firing pin protruding from the bolt. If you don’t see anything; the tip is broken, debris is preventing the full travel of the pin, or you should seriously get your palm looked at because now it is interfering with your PMCS (for all you non-grunts, look it up).
2. Hammer and trigger pins. Check that they are flush with the sides of your rifle. If either is sticking out, it can result in failure, misfire, and burst fire. If it is a hammer pin, just push it back in. The detent in the center of the pin is held in place by the j spring permanently affixed within the hammer itself. If it is the trigger pin, push it back in and move to the next step as a misaligned trigger pin is nearly always caused by a…
3. Hammer spring. A few things can go wrong with this little bugger. To begin with; a properly installed spring, will catch the rear of the hammer just below the disconnect pawl, travel forward and down, coil around the ears/lugs on either side of the hammer, then (from beneath the ears) travel backward over the top of the trigger pin. Also note that one leg of the spring will lay in the trigger pin detent to hold it captive (see the tie-in with the previous step). Two common issues are that the spring is installed backward or the legs are under the trigger pin. Either can result in light strikes or the trigger pin walking out of the receiver. Once you are familiar with what to look for, we can simplify the check list to the following abbreviated form.
1. Twist buffer tube.
2. Buffer retainer pin.
3. Press buffer.
1. Carrier gas key.
2. Gas tube.
3. Cam pin hole.
1. Firing pin retainer pin.
2. Hammer and trigger pins.
3. Hammer spring.