Maintenance of your AR 15 will provide years of proper quality and function from your firearm. We will go through, step by step, to show the proper way to dismantle your firearm and clean it thoroughly.
Step 1: Safety and Ensuring AR is Clear of Ammo
IMPORTANT: Be Sure to Clear Rifle and Remove Ammunition from the Working Area. Before beginning any cleaning of your rifle, always be sure to clear the rifle and remove all ammunition from the area you will be working in just to be safe. Remove the magazine from the AR 15 and lock the bolt in the rear position, so you have a clear visual to ensure no rounds are in the chamber. Release the bolt after verifying and flip on the safety.
Step 2: Separate the Receivers
Separating the upper receiver with the handguard still attached from the lower receiver can be done by either using your fingers or a roll punch to remove the takedown pin towards the rear of the assault rifle and then the pivot pin towards the front. Set the lower receiver aside for the moment.
Step 3: Remove Charging Handle and the Bolt Carrier Group (BCG)
Pull the charging handle back until you are able to remove the BCG from the upper receiver. Once the BCG is removed from the upper, lift and remove the charging handle as well. We’ll focus on disassembling the BCG next.
Step 4: Disassemble the Bolt Carrier Group
To separate the BCG, remove the cotter pin as shown in the photo below using just your fingernails or a pick. After removal of the cotter pin, remove the firing pin and set it aside. No tools should be needed to remove the firing pin as it should fall right out after removing the cotter pin.
Now, push the bolt inward and notice the clocking of the cam pin. Removing the cam pin requires that it be rotated 90 degrees to pass the gas key, as shown below. After the cam pin is pulled out, the bolt can be removed.
Step 5: Disassemble the Bolt
First, remove the extractor pin using a small punch, or the firing pin can be used in place of the extractor pin if you so choose. Once the extractor pin has been removed, set all pieces carefully aside.
Step 6: Cleaning Disassembled BCG Parts
When going through this process, spray all parts with lubricating cleaning oil and scrub away with a nylon brush (or toothbrush). While in the cleaning process, we recommend using some nylon, nitrile, or latex gloves to keep harsh chemicals from coming into contact with your hands. Additional application of the lubricating oil may be needed if parts are very dirty. Once no more residue is showing up, it’s clean. Some areas like bolts may require more attention to remove the carbon buildup. A scraper or wire brush may be applicable here.
Before reassembling, inspect your bolt rings for any damage. Insert the bolt into the bolt carrier and turn it upside down. If the bolt falls out under its weight, you need to change the gas rings. If not, you are good to go.
After you are done cleaning the BCG parts, reassemble them in the opposite order as listed above. Ensure that the bolt is locked correctly into the carrier when you install the cam pin such that the extractor is facing in the direction shown below. Otherwise, the rifle will try to eject casings into the wall of the receiver rather than out the ejection port, likely causing a jam. Some newer designs will only allow installation in one direction, but this isn’t the case for everything out there.
Step 7: Clean Bore and Chamber
Remember when cleaning the barrel, always clean from the rear of your AR 15 to the front. Insert the rod from the breach, not the muzzle. Once a patch or brush has exited the muzzle, please remove it from the muzzle end and do not pull it back through the barrel in reverse. This prevents dirt from being pulled back into your upper receiver. Run a cloth soaked in Bore Cleaner down the barrel and remove it once it has made its way to the end of the muzzle. Repeat this one additional time and then let stand for a couple of minutes to allow the cleaner to work.
Attach a bore brush, insert it through the breach, and slowly push the brush down the barrel until it exits the muzzle. Remove the brush from the end of the rod before pulling the rod back through the barrel. Repeat a couple of times.
If you are using a bore snake, the same principle applies. First, spray some lubricating cleaning oil or run some bore cleaner down the bore. Then lower the brass end from the breach down to the muzzle and finish pulling it out the muzzle.
First, clean the chamber, spray a liberal amount of lubricating cleaning oil into the chamber, and let it sit for a few minutes. Next, insert your chamber brush from the rear of the upper receiver and scrub/twist the chamber and locking lugs for a minute or two.
After using the chamber brush, use a chamber mop, Q-tips or cotton rag clean the area until the residue and crud have been removed. If you have wiped the area dry, lubricate the locking lugs with oil.
Know that failure-to-extract (when a spent casing is not removed from the chamber) is one of the most common issues with the AR-15. This is often caused by a dirty chamber that has built up residue over time, creating a tight fit with the casings. The takeaway here is that the chamber is probably the most critical part of your AR-15 to clean regularly. The BCG is a close second.