Brownells 75th Anniversary - A Shooting Heritage
Menu

Magpul M-Lok Tips

Maximize Your M-Lok Experience With These Tips from Magpul

The M-LOK direct attachment system is extremely intuitive and easy to use. Because of the versatility of the system in accommodating various thicknesses of mounting surfaces and the adjustments that allow this functionality, the tips below will help the user to have the best possible results in the fastest possible time.

AS PACKAGED

  • Your M-LOK accessory may arrive with nuts and nylon patched screws installed as shown in the illustration below. If you are using an adapter or the nuts and screws arrive loose with the accessory you have purchased, then simply thread the nuts onto the screws through the accessory as shown.
  • The nylon patch may seem “stiff” for the first installation of the new screws into the T-Nuts. Using a 7mm wrench to hold the T-Nut to thread it on the screw and then backing it off to the appropriate adjustment will “break in” the nylon patch, and subsequent use will be easy.

  • The nylon patch on the screws actually aids function by providing friction to turn the nuts.
  • If you remove and replace the accessory numerous times, the nylon patch may eventually wear. You also may receive an after-market accessory without the patch on the screws. If the nut is not turning appropriately, the patch effect may be restored with either Rocksett or Loctite blue thread-locker stick. If the screws come without the patch, one of the above products is recommended for best function and durability.

ADJUSTING THE NUT TO THE CORRECT HEIGHT

  • For best function, the T-Nut “gap” must be slightly greater than the thickness of the mounting surface (see pic). This can be done by measuring the mounting surface thickness directly or using the edge of the mounting surface as a gauge. For most aluminum mounting surfaces setting the nuts as depicted below, with the highest edge of the T-Nut even with the bottom edge of the recoil lug, will provide correct function. Some thicker rails or polymer rails may require the nuts to be looser with a one or two thread gap between the nuts and recoil lugs.

  • Some Magpul accessories may arrive preset to the condition shown in the illustration for easy installation on aluminum hand guards. Remember to loosen the nuts a bit for polymer installation.

 

ENSURE THAT THE ACCESSORY IS FULLY SEATED INTO A SLOT WHEN MOUNTING

  • The bottom of the accessory should sit flush with the mounting surface. If it doesn’t then slide the accessory fore-aft until it drops fully into the slot with the lugs engaged.

 

 TURN THE ATTACHMENT SCREWS

  • Apply some downward force on the hex wrench to make sure that the screw is seated, and then tighten. For maximum repeatability, “bias” the accessory before fully tightening.
  • To bias the accessory, apply just enough lateral pressure to the accessory to make solid contact with one side and the front (towards muzzle) of the slot, similar to when installing a Picatinny rail accessory. Then tighten all fasteners fully. This step is not necessary, but aids repeatability.

ENSURE THAT THE NUT ROTATES THE FULL 90 DEG INTO THE LOCKED POSITION

  • If you have adjusted the nuts appropriately, they should rotate into perfect 90 degree alignment with a ¼ turn of the screw.

IF THE T-NUTS ARE NOT ROTATING PROPERLY:

  • When nuts are spaced too far then the nut will rotate freely without stopping and tightening.
  • In this case the nut will have to be screwed in closer to the bottom of the accessory. Simply remove the accessory from the slot and screw the nut on one full turn. Repeat as necessary so that the cam engages the slot when the screw is tightened.
  • If the nut is spaced too close to the accessory, then the “wings” of the nut will contact the sides of the slot and the nut will not rotate into place. This will cause the nut to tighten against the accessory lugs without engaging the hand guard.
  • In this case the nut should be unscrewed until it is spaced far enough away from the lugs to allow it to rotate properly into position. Unscrew the nut one turn at a time and retest function.

 

IT IS BEST TO OBSERVE THE NUT ROTATING, IF POSSIBLE, TO BE CERTAIN THAT IT TURNS FULLY IN TO PLACE, OR TO CHECK IT AFTER TIGHTENING IS COMPLETE

  • Most hand guards or other mounting surfaces have holes or vents that can be seen through to confirm that the M-LOK T-Nuts are properly engaged with the slot, 90 degrees from slot orientation.
  • If it is not possible to watch the nut rotate, then careful attention needs to be paid to the screw as it is tightened. The screw should turn easily for the first quarter turn, then when the nut stops rotating it will become slightly more difficult to turn. Continue tightening until secure. Pull on both ends of the accessory to ensure it is engaged.

TORQUE SPECS

  • For attaching metal accessories to metal hand guards: 35 in/lbs
  • For attaching polymer or metal accessories to polymer hand guards: 15 in/lbs
  • For attaching polymer accessories to metal hand guards: 15 in/lbs
  • The installation torque values are not minimums, they are recommended limits. The nylon patch compound may slightly affect the torque reading if using an in/lb torque wrench.
  • Using a small hex wrench should prevent over-tightening. Remember that the recoil lugs are doing most of the work, and excessive torque on the nuts is not required.

IF YOU DON’T HAVE AN IN/LB TORQUE WRENCH, HERE ARE SOME TORQUE GUIDELINES:
35 in-lb using the long arm of an L-wrench (short end in screw)

  • Standard 2-5/16” wrench
    • Apply 15 lb to the end of the wrench
    • Approximately 1/4” deflection at the end of the wrench
  • Long 3-13/32” wrench
    • Apply 9 lb to the end of the wrench
    • Approximately 1/2” deflection and the end of the wrench

15 in-lb using the long arm of an L-wrench (short end in screw)

  • Standard 2-5/16” wrench
    • Apply 6.5 lb to the end of the wrench
    • Approximately 3/16” deflection at the end of the wrench
  • Long 3-13/32” wrench
    • Apply 4 lb to the end of the wrench
    • Approximately 1/4” deflection and the end of the wrench

15 in-lb using the short arm of an L-wrench (long end in screw)

  • Apply maximum force achievable by hand

REMOVAL

  • To remove, simply loosen the accessory mounting screws one full turn and the T-Nuts should loosen and align with the slot to be easily removed.
  • If the T-Nuts snag when passing through the slot, simply pull up gently on the accessory and continue to loosen the screw another ¼ to ½ turn, which should align the T-Nuts with the slot.
  • On some polymer mounting surfaces, the T-Nuts may embed slightly into the polymer surface when tightened.
  • When removing from polymer surfaces, easiest function is obtained by loosening ½ turn or so and then pressing down on the head of the screw with the hex wrench. This will free the T-Nut if it has been over tightened, and you may remove normally after this step.
  • If you go too far in loosening before removing the accessory, the T-Nuts may have loosened past the slot to the point that they will not engage and are spinning freely. In this case, gently pull up on the accessory until the T-Nut cams engage the slot, and then they will turn to align with the slot as the screw is loosened further.