CMC Triggers Adjustable Gas Block Low Profile Fits AR 15 750 Black CMC GB ADJ 750 UPC 810169561799
Product Description
The CMC Triggers® .750" Low-Profile Adjustable Gas Block (SKU: CMC-GB-ADJ-750 / UPC: 810169561799) gives builders, suppressed shooters, and 3-Gun competitors complete mechanical authority over their AR-15's cyclic rate and recoil impulse. Most factory AR-15 barrels feature oversized gas ports designed to cycle weak commercial ammunition in freezing conditions—resulting in violent bolt carrier velocity, premature extractor wear, excessive felt recoil, and toxic gas blowback when running a sound suppressor or full-power 5.56 NATO loads. The CMC Adjustable Gas Block eliminates over-gassing at the source by allowing precise metering of gas flow entering the gas tube.
Precision CNC-machined in Texas from solid ordnance steel and finished in a rugged, corrosion-resistant black phosphate coating, SKU CMC-GB-ADJ-750 withstands extreme port erosion and sustained firing schedules. Its streamlined low-profile silhouette slips effortlessly beneath modern slim-diameter free-float M-LOK and KeyMod handguards—making it the ideal companion to the CMC Triggers Texan handguard family.
Engineered for the industry-standard .750-inch barrel gas journal, this complete assembly ships ready to install with two bottom-locking knurled set screws, a gas tube roll pin, and the gas metering adjustment and locking screws. Once tuned to lock the bolt catch open on an empty magazine with your preferred ammunition or suppressor configuration, the secondary locking set screw secures your gas setting against vibration drift for rock-solid reliability.
*Armorer Bench Notes & Real-World Staging Guidance:*
Fitment Matrix: Fits all AR-15 and AR-10 barrels machined with a standard .750" OD gas block journal. CRITICAL FITMENT & TUNING WARNING: Measure your barrel's gas journal with calipers prior to ordering—this block will NOT fit .625" pencil barrels, .875", or .936" bull barrels. Leave a 0.025" to 0.030" gap (roughly the thickness of a plastic credit card) between the rear of the gas block and the barrel shoulder unless your barrel is specifically machined for flush contact, as standard AR-15 gas ports are drilled to align with the thickness of an A2 front sight base handguard cap.
- Ensure the host firearm is completely clear, magazine removed, and chamber visually and physically verified empty before beginning upper receiver disassembly.
- Insert your gas tube into the CMC .750" Adjustable Gas Block (orienting the gas tube port hole downward to align with the block's internal transfer port) and drive the included gas tube roll pin flush through the top cross-bore using a roll pin starter punch.
- Slide the gas block assembly over the barrel's .750" gas journal while guiding the gas tube through the barrel nut and upper receiver; align the bottom set screw bores with your barrel's dimple(s) and verify top dead center gas port alignment.
- Apply high-temperature threadlocker (such as Rocksett or Red 271/2620) to the two bottom mounting set screws and torque them evenly to 25–30 in-lbs.
- At the range, turn the main gas adjustment screw clockwise until lightly seated (closed), then back it out 1.5 turns; fire single rounds from an empty magazine, opening the screw in 1/4-turn increments until the bolt locks back reliably on the last round plus an additional 1/4 turn for operating margin, then snug the secondary locking set screw to secure the setting.
Key Features
- Custom Gas Volume Metering: Tunes gas flow at the barrel port to tame felt recoil, eliminate brass over-ejection (tuning for a clean 3:30 to 4:00 ejection pattern), and reduce carrier velocity.
- Optimized for Suppressed Shooting: Dramatically cuts backpressure and chamber blowback into the shooter's face when running baffled sound suppressors.
- Low-Profile Under-Rail Geometry: Compact outer profile clears virtually all modern free-float M-LOK, KeyMod, and quad-rail handguards.
- Ordnance Steel Construction: CNC-machined steel body with a black manganese phosphate finish resists high-pressure gas erosion and thermal expansion.
- Complete Hardware Package Included: Ships with (2) bottom barrel mounting set screws, (1) gas tube roll pin, and gas adjustment/locking screws.
Product Specifications
- Brand: CMC Triggers®
- Model/Series: Low-Profile Adjustable Gas Block (.750")
- MPN / SKU: CMC-GB-ADJ-750 / CMCGBADJ750
- UPC: 810169561799
- Platform Compatibility: AR-15 / AR-10 Barrels w/ .750" OD Gas Journal
- Inside Diameter (Journal Bore): 0.750 in (.750")
- Attachment Type: Dual Bottom Set Screws (Included)
- Material: CNC-Machined Ordnance Steel
- Finish / Color: Black Manganese Phosphate
- Included Hardware: (2) Mounting Set Screws, (1) Gas Tube Roll Pin, & Adjustment/Locking Screws
- Country of Origin: USA
