Safety & Maintenance Instructions

FREEDOM. PASSION. PRECISION.

™

3.9

ADJUSTABLE GAS BLOCK

The DD Adjustable Gas Block is a two-position adjustable gas block designed with

suppressors in mind. The gas block has a 90-degree throw between the unsuppressed

and suppressed modes. A unique feature of the gas block is that it can be quickly

adjusted through the side of the rearm’s handguard by rotating the throw lever with the

DD supplied Allen wrench.

4.0

FUNCTION

Daniel Defense rearms have semi-automatic actions. With the action cocked, chamber

loaded, and selector lever set to “SEMI,” the rearm may be red by squeezing the

trigger. The trigger pivots, disengaging the trigger sear surface from the hammer. The

hammer spring drives the hammer forward to strike the ring pin, which in turn strikes

the primer in the base of the cartridge, igniting the priming compound, which ignites the

main powder charge. High-pressure gases produced by the powder charge push the

bullet down the barrel, where riing grooves impart a stabilizing spin to the bullet. As

a bullet passes the gas port (a small hole in the top of the barrel below the gas block),

gas escapes through the port, ows through the gas tube into the bolt carrier chamber,

driving the bolt carrier group rearward. As the bolt carrier moves to the rear, the ring

pin is withdrawn into the bolt while the cam track in the bolt carrier acts upon the bolt

cam pin, causing the bolt to rotate until its locking lugs are no longer in engagement

with the lugs of the barrel extension. The bolt is now unlocked and is carried rearward

by the bolt carrier. The extractor extracts the spent case and holds it against the face

or bolt until the ejector throws the spent case through the ejection port. The bolt carrier

group continues rearward, compressing the action spring and returning the hammer to

its cocked position until the buffer assembly strikes the bottom of the receiver extension

and stops. The action spring then forces the bolt carrier group forward as the face of

SUPPRESSED UNSUPPRESSED