The MFR Rail System is a full-length, free-float, M-LOK® handguard for the AR-15 from Daniel Defense. The MFR's mounting system is pretty similar to other Daniel Defense handguards, but it requires a few tricks. Brownells Gun Tech™ Caleb Savant shows us exactly how to install it. The MFR is designed to fit a standard mil-spec AR-15 upper receiver. It will also fit a machined billet upper that is cut to mil-spec dimensions at the front (Caleb shows us where).
TOOLS: You'll need the (1) barrel nut wrench, (2) ball-tip hex wrench, and (3) tube of thread-locker that came with the MFR Rail. You'll also need (4) a bench vise, (5) an adjustable torque driver, (6) the Midwest Industries Upper Receiver Rod or similar device to hold the upper receiver in the vise, and (7) Brownells Action Lube Plus® or similar high-quality gun grease.
PHASE 1: Use the Upper Receiver Rod or a vise block to clamp the receiver securely in the vise. Put a little Action Lube Plus on the barrel extension, slide the barrel into the receiver, and put a dab of grease on the barrel extension's front shoulder. Get the mounting plate that has tabs protruding from one side and insert the bolts through the holes from the tab side. Slide the plate over the barrel, with tab side facing TOWARD the receiver. Apply some lube to the threads of the barrel nut, slide it over the barrel, and hand-tighten it onto the receiver. Tighten the barrel nut the rest of the way using the Daniel Defense wrench and your adjustable torque driver set to about 35 ft.-lbs.
PHASE 2: Slide the other MFR mounting plate over the barrel with the INLETTED side facing the bolts (flange side toward the muzzle) and press it up against the first plate. The bolts will go through the holes in Plate #2. Install your gas block and gas tube. You'll know you have the MFR plates properly oriented if holes line up to allow the gas tube to slide into the receiver! Slide on the handguard up to the bolts. Put a little thread-locker on each bolt. Use the hex wrench to snug up the bolts. Don't tighten them all the way yet......
PHASE 3: Check for gaps between the handguard, the mounting plates, and the front of the receiver. If everything's snug, tighten the bolts the rest of the way. There's no specific torque setting. Just make 'em tight enough so the MFR is securely anchored with no wobble or play.
DONE: Your Daniel Defense MFR Rail System handguard is properly installed on the upper receiver. It's time to add your chosen muzzle device and whatever accessories you want to put on the MFR!
NOTE: Products in this video are to be used only for lawful purposes, including hunting, self-defense, and competitive or recreational shooting. If you purchase any of them, you are responsible for understanding and complying with all federal, state, and local laws that apply to the purchase, possession, and use of these products.
