Faxon Patented Adjustable 3 Screw Low Profile Gas Block

The Faxon Patented Adjustable 3 Screw Low Profile Gas Block meters gas by moving the gas tube rather than by threading a screw into the gas passage. The tube is pinned to an adjustment plate, and the adjustment screw slides that plate fore and aft so the tube inlet moves into or out of line with the passage. Because the screw never sits in the gas stream, carbon has no exposed threads to pack and seize. Faxon holds U.S. Patent No. 12,716,670 B2 on the design, issued August 25, 2026.

The block gives 14 spring-detented settings from fully open to fully closed. A spring inside the mechanism presses into notches machined into the screw head, so each setting is a felt click that holds under recoil and heat cycling. The adjustment screw sits on the rear face of the block, and Faxon has you tune it from the receiver side through the handguard's slots with a 3/32 inch hex key or a flat screwdriver.

Faxon machines the block from 4140 chromoly steel with a black flash-nitride finish in Ohio and mounts it with three 10-24 set screws on the bottom. Each journal size is its own SKU: .625 for thin profiles such as the Faxon Pencil and Gunner in 5.56 and .223 Wylde, .750 for most standard and mid-weight AR-15 and AR-10 profiles, and .875 for heavy profiles and large-frame barrels such as 8.6 Blackout. Every size is 1.000 inch long; the .750 block measures .899 inch across the body and 1.350 inch tall to the top of the gas-tube boss. The gas tube is sold separately, and any standard AR tube in pistol, carbine, mid, or rifle length works. During installation the tube pins to the adjustment plate rather than the block body, with the plate set fully forward (fully closed) before pinning.