The MMRB-556-18 rifle combines modern features with classic lines. The MMRB-556-18 contains the same components as the MMRB-556, but incorporates an 18″ barrel, and Magpul Industries MLOK rifle handguard. This combination results in a slightly more cost effective rifle that is still suited for extremely hard use.

At the heart of our rifles, we use our M16 cut nitride bolt carrier group, matched with a fully nitrided Ballistic Advantage 18” mid-length barrel. Our rifle-length gas system provides an extremely soft and controllable recoil impulse.

Our MPP-GI trigger has micro polished contact surfaces, and a fitted disconnector. This combination gives you the 5lb weight of a typical duty trigger, and removes all of the gritty drag while breaking the shot. Our fitted disconnector gives a positive, short reset that is hard to miss!

2 in stock


2 in stock

Forged Lower Receiver:

• 7075-T6 Forged Aluminum

• Hard-Coat Anodized Mil 8625 Type 3 Class 2 – Matte Black

• Upper Receiver Tension Screw with nylon tip to remove any slack between lower and upper receiver.

• Detent Set Screw for rear take-down pin (captures spring that is normally held in by the end plate.)

• Bolt Catch Screw (Used in place of the Bolt Catch roll pin)

• Custombilt MPP Trigger: (Micro Polished Performance) GI Trigger

• Custombilt Enhanced Trigger Guard

• Rifle Buffer Tube, Rifle Buffer, Stainless Steel Spring

• Magpul CTR Stock

• Magpul MOE Grip

• Mil-Spec Safety Selector

• 30 round magazine

Forged Upper Receiver:

• 7075-T6 Forged Aluminum

• T-Marked Flat-Top with Picatinny Rails

• Hard-Coat Anodized Mil 8625 Type 3 Class 2 – Matte Black

• Mil-Spec Charging Handle


•Magpul MLOK Rifle


• 18″ Barrel (1:7 twist)

• 4150 Chrome Moly Vanadium

• Nitride/QPQ Finish

• Thread: 1/2 x 28

• A2 Flash Hider

• Pinned Front Sight Block

• Rifle- Length Gas System

Custombilt M16 Bolt Carrier Group:

• Properly staked gas key

• Nitride Coated

• Laser Engraved Custombilt Logo

• HPT – High Pressure Tested

• MPI – Magnetic Particle Inspected

• 9310 Bolt

• 8620 Bolt Carrier