Quick Answer

To install a 15-inch M-LOK handguard on your AR15, you'll need to remove the old handguard, swap the barrel nut if required, and torque everything to spec. Use a vice block and torque wrench to ensure a secure, straight fit.

Why Choose a 15-Inch Free Float Handguard?

A 15-inch free float handguard extends past the gas block, giving you more rail space for accessories and better accuracy because it doesn't touch the barrel. However, it's heavier and may require removing the gas block or front sight base if they're in the way.

Make sure your rifle's gas block is low-profile or that you're willing to swap it. If you have a front sight base, a 15-inch rail may not fit without modification.

Tools You'll Need

Gather a vice block, torque wrench, Allen keys, and anti-seize compound. Most M-LOK handguards include the barrel nut and hardware, but check your kit before starting.

Step-by-Step Installation

  1. Safety Check and Prep: Ensure the rifle is unloaded and remove the upper receiver from the lower. Secure the upper in a vice block to prevent movement. Always double-check that the chamber is empty before starting.
  2. Remove the Old Handguard: If you have a carbine handguard, remove the delta ring or any screws holding it. For free float handguards, loosen the set screws and twist off the rail. Keep all small parts in a container so they don't get lost.
  3. Remove the Gas Block (If Needed): If your gas block is not low-profile, remove it to allow the 15-inch handguard to slide over. Use a punch to drive out the taper pins or loosen the set screws. Mark the gas block position before removal to make reinstallation easier.
  4. Install the New Barrel Nut: Apply anti-seize to the barrel nut threads, then hand-tighten the new barrel nut. Use a torque wrench to tighten to the manufacturer's spec (typically 30-80 ft-lbs). Check the included instructions for the exact torque range for your handguard.
  5. Slide on the Handguard: Align the anti-rotation tabs and slide the handguard over the barrel nut. It should fit snugly without forcing. If it doesn't slide on easily, check for burrs or misalignment.
  6. Secure and Torque the Handguard: Use the provided Allen key to tighten the set screws to the recommended torque (usually 15-20 in-lbs). Avoid over-tightening. Over-tightening can strip the threads or damage the rail.
  7. Reinstall the Gas Block and Accessories: If you removed the gas block, reinstall it and ensure it's aligned. Then attach your M-LOK accessories using the slots. Verify the gas block doesn't contact the handguard and that the gas tube is clear.

Product Spotlight

  • AR15 15" Slim M-LOK Handguard Rail One Piece Free Float: This 15-inch ultra-light slim M-LOK handguard is one-piece free float, made from 6061-T6 aluminum, and includes a steel barrel nut, Allen key, and crush washers. The included barrel nut and hardware mean you don't need to buy extra parts, and the 3-side M-LOK slots give you plenty of mounting options.

    AR15 15" Slim M-LOK Handguard Rail One Piece Free Float

    AR15 15" Slim M-LOK Handguard Rail One Piece Free Float