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How To Perform An AR-15 Rifle Function Check

Are you regularly performing a functions check on your primary AR rifle? Here is how and why you should be on a regular basis.

How To Perform An AR-15 Rifle Function Check

A pre-shift equipment check is part and parcel to being a cop. From making sure the patrol vehicle’s tires are properly inflated to confirming the emergency lights are working, an officer can’t afford to start a shift wondering about the status of life-saving equipment. This is especially true when it comes to the status of an officer’s patrol rifle. Not only does a patrol rifle function check confirm that the rifle is operational, but it also serves as an excellent opportunity for the officer to handle the rifle before each shift. When done properly, this has a carryover effect that can help the officer run the gun more efficiently. But you don’t need to wear a badge to benefit from function checking your AR-15.


By loading a mag with dummy rounds, you can safely check an AR’s feeding function at home.

The purpose of a function check is to confirm every component of your AR-15 is in proper working order. It’s not only meant to uncover mechanical issues that could disrupt the cycle of operation but also to identify problems with accessories that could compromise aiming, illuminating, etc. But there’s another benefit to conducting a function check on a regular basis. A function check entails manipulating the AR-15 controls, which breeds familiarity. If you hadn’t picked up your AR-15 in months and suddenly needed to defend yourself, you may be relearning how to operate it on the fly — not a good strategy. For maximum benefit, perform the function check in a way that reinforces proper gun handling. To be sure your function check is thorough and complete, it’s a good idea to conduct it the same way every time. If you start with the weapon-mounted light one time and the forward assist the next, there’s a good chance you’ll eventually overlook something. But before we get into the process of function checking your AR-15, it’s critical that the following safety measures be adhered to.

Safety First

Conduct the function check in an area where the muzzle can be pointed in a safe direction. Ensure the selector switch is on Safe. If there’s a magazine in the well, remove it. Cycle the bolt several times then lock it to the rear. Now, visually, and physically ensure the chamber is clear by looking through the open ejection port and then sticking your finger up through the magazine well to feel the chamber. With the rifle confirmed unloaded, ensure there is no live ammunition on the room. Now, you’re ready to begin.

How to Perform an Functions Check


There is more than one way to function check your AR-15. As you’ll see, I start with bolt and trigger functionality because without that, does the status of the weapon-mounted light or stock really matter? Some may prefer to start at the front or the rifle and work their way back or vice-versa. If your function check is systematic and thorough, the order in which you test the various functions is unimportant.

    1. Close the bolt: With the bolt open on an empty AR-15, ensure the mechanical safety is engaged. The selector switch should be pointed forward in the horizontal position.  Point the muzzle in a safe direction and close the bolt. This can be accomplished a few different ways. A righty could use their left thumb or the heel of their left hand to depress the bolt release. The former is faster, while the latter is more gross motor-based and therefore easier to perform under duress. Be consistent. Choose one technique and stick to it, so you’re not trying to decide which technique to employ during an armed encounter. Lefties will need to get creative and either depress the bolt release with their index finger or reach around the magazine well and use their right hand to hit the release. Again, consistency is key. Whichever technique you use, make sure the bolt moves all the way forward. This is also a good prompt to hit the forward assist with your right palm. If the bolt isn’t fully closed, hitting the forward assist can nudge the bolt forward into battery.
    1. Test bolt and trigger functionality: Push forward and downward on the selector switch so that it’s in the vertical position. With a traditionally configured AR-15, the selector switch is on the left side, allowing righties to manipulate it with their thumb but requiring lefties to use their left index finger. An ambidextrous selector switch enables lefties to use their left thumb on the right-sided selector switch. Now, press the trigger and hold it to the rear. You should hear a click as the hammer strikes the firing pin. With the trigger held back, use your non-firing hand (referred to as your support hand) to pull the charging handle completely to the rear. For righties, this can be done by pinching the left side of the charging handle between your thumb and index finger or by hooking the charging handle with the base of your pinky. Release the handle to send the bolt home. Resist the temptation to run the charging handle with your firing hand. Like loading a magazine with your firing hand, this is inefficient. To the extent possible, your firing hand should be on the pistol grip, ready to move the selector switch and press the trigger as required. Finally, after running the charging handle, release pressure on the trigger, allowing it to move forward. You’ll hear a click and feel a jolt as the sear resets.
    2. Test mechanical safety: After simulating firing the AR-15, you’ll want to confirm the mechanical safety is working. Manipulate the selector switch to Safe by reversing the process you used to switch it to Fire. Press the trigger. While there’s bound to be some movement, the trigger shouldn’t move much and certainly not all the way back.
Check your irons and optics to ensure proper function.
  1. Check magazine insertion, removal, and feeding: Insert an unloaded magazine into the well and make sure it locks into place by giving a tug after firmly inserting it. Then hit the magazine release to ensure the magazine falls from the well. To ensure your AR-15 is feeding properly, you can conduct a simulated “press check” with inert dummy rounds. Rather than ease the charging handle back as you would the slide on a pistol and risk inducing a malfunction, try this. Before inserting the magazine with at least two dummy rounds (no live rounds!) into the AR-15, take note of which side of the magazine the top round is on. If you insert the magazine and cycle the bolt, you can confirm there is a round in the chamber by removing the magazine and checking to see if the top round has switched sides. If so, the “missing” round is in the chamber.
  2. Check the stock: If the stock is telescoping or folding, check to make sure it’s functioning as intended.
  3. Check accessories: Now that you know the rifle is functional, it’s time to check the accessories. Is everything tightly attached? Does the optic or weapon-mounted light need a battery replacement? Do the backup iron sights (BUIS) flip up and down as designed? If you’re using a sling, is it properly adjusted?


After seeing that your magazine inserts and feeds properly, press the magazine release button to ensure it falls from the well. While function checking, if the bolt does not move all the way forward, press the forward assist to push it into battery.

When conducting a function check, your goal should be to find a problem. If that’s not your mentality, you’re just going through the motions. If you detect a problem that can easily be remedied by cleaning, lubricating, tightening, or replacing batteries, handle it. If the problem is more complex, you’ll either need to bone up and try your hand at fixing it or get it to someone with more knowledge and experience. Most of the time, your function will simply confirm that your AR-15 is in good working order.

Now What?

Assuming the function check didn’t reveal any problems, it’s time to set up the AR-15 the way you intend to store it. When I was a cop, we stored the AR-15 in a condition known as “patrol ready.” This entailed inserting a Hornady Rapid Rack into the chamber and easing the bolt forward. (The Rapid Rack prevents the bolt from closing completely). A loaded magazine was then inserted. The selector switch was on Safe. To deploy, I would first disengage the AR-15’s locking mechanism to remove the rifle from the patrol vehicle. Then, with the muzzle pointed in a safe direction, I would pull the Rapid Rack rearward, which ejected it from the chamber and replaced it with a live round. Obviously, how you store your AR-15 is a personal decision that’s based on the balance between security and accessibility that the situation demands.


Can you imagine reaching for your AR-15 in an emergency only to realize it doesn’t work? This unacceptable outcome is easily avoided with regular function checks. Not only is function checking your AR-15 necessary to make sure it will go bang when you pull the trigger, but it’s also a great way to sneak in extra training. For a function check to be beneficial from a training perspective, you’ll need manipulate the AR-15 as you would in a self-defense situation. That means using your support hand to perform all tasks except manipulating the selector switch, pressing the trigger, hitting the forward assist, and depressing the bolt catch to lock the bolt open. A proper function check ensures your AR-15 is operational and your gun handling skills stay sharp. Viewing the function check as a mini-training session is a great way to kill two birds with one stone. If there is a problem, you will find it and take appropriate action. If everything checks out, the function check allowed you to get in some extra gun handling.

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