How to Cure Bolt Carrier Drag on an AR-15

The AR-15 is a popular semi-automatic rifle, prized by shooters and collectors alike for its accuracy and the clean lines of its design. However, like its militarized version, the M-16 assault rifle, it's also known as a high-maintenance weapon. Any grit or fouling that collects in the action can cause the bolt carrier assembly to drag, which in turn results in failures to feed and/or failures to extract spent cartridges. When a fouled bolt carrier causes your AR-15 to malfunction, a simple field strip and clean won't get the job done. You'll have to disassemble the upper receiver and give the entire bolt carrier group a detailed cleaning.

Things You'll Need

  • Drift pin
  • Penetrating gun cleaner/lubricant
  • Worn bore brush
  • Cleaning patches
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Instructions

  1. Disassembling the Rifle

    • 1

      Place the rifle in a vertical position, with the back of the butt stock resting on a stable work surface. Push down on the slip ring at the base of the handguards, then remove the handguards.

    • 2

      Use a drift pin or the tip of a bullet to press in the take-down as far as it will go. The take-down pin is located on the left side of the receiver, just above the fire selector switch. Swing the back of the upper receiver away from the lower receiver.

    • 3

      Push in the receiver pivot pin and slide it out from left to right. Separate the upper receiver assembly from the lower receiver.

    • 4

      Turn the upper receiver so the bottom faces upward. Pull back on the charging handle to slide the bolt carrier out of the rifle. Remove the bolt carrier and bolt from the rifle and set them on your work surface. Remove the charging handle by pulling it back and up.

    • 5

      Push the firing pin retaining pin out of the bolt. Use a drift pin to get it started, then pull it out the rest of the way by hand.

    • 6

      Place the bolt in the locked position by pushing into the face of the bolt carrier. Turn the bolt cam a quarter-turn counterclockwise and pull it out of the the bolt. Slide the firing pin out the rear of the bolt carrier, then remove the bolt from the carrier.

    Cleaning and Lubricating

    • 7

      Scrub thoroughly all pieces of the bolt and bolt carrier assembly using a penetrating cleaner. Use a worn bore cleaning brush to work the outer and inner surfaces of the bolt carrier, the carrier key, the firing pin recess and the firing pin. Make sure to remove any carbon deposits or fouling from the locking lugs and around the extractor.

    • 8

      Wipe cleaning residue off all parts using either a clean rag or gun cleaning patches. Dry the carrier key, firing pin recess and the firing pin hole using a pipe cleaner.

    • 9

      Moisten a cleaning patch with lubricant and lightly rub down the firing pin and firing pin recess. Use the same method to lubricate the extractor, charging handle and the inner and outer surfaces of the bolt carrier.

    • 10

      Soak a cleaning patch in lubricant, then apply a heavy coat of lubricant to the exterior of the bolt. Similarly apply a heavy coat of lubricant to the bolt carrier slide and around the cam pin.

    • 11

      Reassemble the rifle by following the steps in Section 1 in reverse order. Test fire the rifle, noting in particular the function of the bolt and extractor. Any failures to feed or eject cartridges may indicate more serious mechanical problems with the weapon, which should be addressed by a qualified gunsmith.