How to Clean an AR

How to Clean an AR Lower Receiver

Attach the shotgun bore mop onto the cleaning rod handle. If you have opted for the bore brush + wipe option, install the bore brush on the handle and wrap a wipe around it (wrap enough times to get between 3/4″ and 1″ diameter).
Insert the bore mop fully into the receiver extension. Wipe around the inner diameter of the receiver extension as you pull the bore mop out.
Shine a light into the receiver extension and inspect.
- Look for any debris remaining in the tube. Repeat step 2, as necessary.
- Look for any pitting, cracking, or unusual wear. Replace the receiver extension, as necessary.
- Inspect the staking of the castle nut, as applicable. If the staking is not sufficient, re-stake the castle nut per the How to Build section Step L9.7.

Using a clean and dry wipe, wipe the buffer spring or buffer assembly thoroughly to remove all lubricant and debris.
Inspect the buffer spring for wear or damage.
- Measure the length of the buffer spring to determine if it has shortened excessively. Replace the buffer spring, as necessary.
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- Inspect the buffer spring for kinks or cracking. Replace the buffer spring, as necessary.
Using a clean and dry wipe, wipe the buffer, if applicable.
Inspect the buffer for wear and damage.
- Look for gouging on the face of the buffer (where the BCG strike it). Replace if excessive gouging has occurred and continue to Toubleshoot.
- Look for excessive scratching, gouging, and any cracking of the buffer body. Replace the buffer, as necessary.
- Inspect the bumper of the buffer for cracking or mushrooming. If the bumper looks beat to hell and is wider than the body of the buffer, you may have an over-gassed gun; proceed to Toubleshoot. Replace the buffer, as necessary.

Using a nylon brush, brush the trigger assembly, including trigger, hammer, and springs, to loosen any debris.
Using a clean and dry wipe, wipe the hammer.
Inspect the hammer and disconnector for unusual wear or damage.
- Inspect the striking face of the hammer for gouges, chips, or cracks. Replace the hammer or trigger group, as necessary.
- Inspect the hook of the disconnector and hammer for chipping or excessive wear. Replace the disconnector, hammer, or trigger group, as necessary.

Using a nylon brush, wipes, cotton swabs, scraping tools, and compressed air, clean any debris out of the interior of the lower receiver.
Wipe the out the interior of the lower receiver.
With the pivot and takedown pins in the open position, wipe the shafts of the pins with a clean and dry wipe.
Inspect the lower receiver and components for unusual wear or damage.
- Inspect the pivot and takedown pins for wear or cracking. Replace the pin(s), as necessary.
- Inspect the pin holes for the safety selector, pivot pin, takedown pin, trigger pin, and hammer pin for excessive wear or cracking. If observed, you may need a new lower receiver.
- Verify the locking of the pivot and takedown pins in the open and closed positions. If the pins are not secured by the detent, the detent, detent spring, or pin may need to be replaced.
- Inspect the bolt catch for excessive wear, chipping, or cracking. Replace the bolt catch, as necessary.
- Inspect the bolt catch lugs on the lower receiver for cracking. If present, you may need to replace your lower receiver.
- Inspect the magazine catch for excessive wear, chipping, or cracking, especially where the magazine catch latches the magazine. Replace the magazine catch, as necessary.

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