Dirty Bird AR-15 SMRS Handguard – Slim M-LOK Rail System

The SMRS (Slim M-LOK Rail System) by Dirty Bird Industries is a high quality and feature packed M-LOK hanguard designed for AR-15 platform rifles and pistols. When designing this handguard, the team started from a basic set of requirements: The handguard must be tough, versatile, practical and have a straight forward install.

NEW: This version features new patent pending anti-slip / anti-lift attachment method (ASAL^TM) for an easy, timing-free installation that provides an extremely rigid and secure attachment. Read below for more technical details about this impressive new attachment method.

Tough

• Machined from aircraft grade 6061-T6 aluminum extrusions.
• Anti-rotation tabs.
• Type 3 hard anodizing or Cerakote™ sprayed at 1 mil thickness per spec.

Versatile

• M-LOK attachment slots on all sides (except top)
• 1913 Picatinny top rail with shaved and beveled center section.
• Raised QD attachment points at the 3 and 9 o’clock positions.
• Snag free design with smooth, uniform octagonal surface ideal for accessory attachment or application of specialty coatings or patterns.

Practical

• Aircraft Grade aluminum barrel nut. In our tests, the aluminum barrel nuts are just as effective when torqued to spec. Additionally, the weight savings enable us to utilize a longer barrel nut design which means more surface area at the attachment point without adding unnecessary weight.
• Compatible with most known low profile gas blocks.

Straight Forward Installation

• No frills clamp-on style installation using only a 1-3/16 Crow’s Foot wrench and 5/32″” Allen key
• Barrel nut does not requiring timing with the gas tube. No shims required.

The end result is a great looking, zero compromise handguard suitable for a wide variety of builds.

Made in the USA

Dirty Bird Industries’ Limited Lifetime Warranty

Available Colors

Black, Magpul™ FDE, Magpul™ OD Green, Midnight Bronze, Sniper Grey

Interior Diameter

1.35″” ID

1.7″” Maximum Vertical ID (for considering vertical height of gas blocks)

Weight (including mounting hardware)

9.5″” – 9oz

13.5″” – 11.4oz

15″” – 12.4oz

ASAL Attachement System Report

Eliminating Handguard Slip

The shockwave generated when firing an AR-15 creates over 1000 G’s of acceleration. This means that a one pound part will generate over 1000 pounds of force every time the rifle is fired. Combined with the thermal cycling generated when firing multiple rounds, it can be very difficult to keep a handguard from slipping forward or rotating. Many attempts have been made to solve this problem. Some solutions are overly complex, resulting in difficult installation and high manufacturing cost. Some designs, like the popular key seat, are overly simple. The key seat will stop a handguard from coming completely off of the rifle; however, it still allows some forward slip and 360 degrees of rotation.

Handguard Lift

Free-floating handguard mounting systems tend to produce an upward lift of the handguard, resulting in the muzzle end of the handguard floating higher than the receiver end. This lift can adversely affect the performance of the rifle, especially when using iron sights. Even if the handguard is only used for protecting your hand, a small amount of lift is noticeable when aiming down the sightline. This visually makes the rifle seem crooked. Even if the rifle performs with precision, it can create an optical illusion, thereby reducing accuracy.

Solution

The patent pending ASAL^TM (Anti-Slip / Anti-Lift) system is simple, easy to install, easy to manufacture, and a cost effective solution to handguard slip and lift issues. The ASAL^TM system locks the handguard to the barrel nut using a CamLok^TM fastener featuring a 10 degree taper angle. This small taper creates a huge mechanical advantage, greatly increasing the force generated by a standard screw. The mating groove in the barrel nut is offset so as it is tightened, the handguard is pressed against the upper. This mitigates lift while also preventing slipping or rotation around the barrel’s axis. The result is a handguard that will not slip, rotate, or lift.

The result is a 10x decreases of handguard muzzle end lift.