The Riflespeed adjustable gas block with a .750-inch journal and a 2.1-inch assembly (brand part no. RS7521) lets you tune the gas on an AR-15 or AR-10 without tools. A numbered control knob clicks at every setting, so each adjustment is repeatable and you can return to a known setting for suppressed fire, different ammunition or changing conditions. The last two digits of the model number give the assembly length, which is 2.1 inches on this one. It requires a straight gas tube, which Riflespeed sells separately.

Key Specifications

• The journal diameter is .750 inch, so it fits barrels with a gas block journal of that size.
• The assembly length is 2.1 inches, the dimension to check against your handguard and muzzle device.
• Adjustment is tool-free through a numbered control knob with tactile clicks, so settings are easy to read and repeat.
• A rotation stop keeps the knob from turning far enough to unintentionally disassemble the control.
• It requires a straight gas tube, either Riflespeed or an equivalent, and the tube is not included.

Frequently Asked Questions

How do I know if the 2.1-inch assembly is the right length? Riflespeed says an ideal fit places the control knob 0.5 to 2.0 inches beyond the front of the handguard, with at least 0.4 inch exposed for access. If more than one length fits, Riflespeed generally recommends the shortest.

Which cartridges does it work with? Riflespeed lists .223 Remington and 5.56x45mm, 300 AAC Blackout, .308 Winchester and 7.62 NATO, 6.8 SPC and 6.5 Grendel, and says the modular design covers other cartridges.

Buy the Riflespeed Adjustable Gas Block, .750-Inch Journal, 2.1-Inch Assembly

Riflespeed built its gas controls to be set once and repeated, so changing ammunition or adding a suppressor no longer means guessing at the gas. Order it from our Lubbock, Texas gun shop for fast, insured shipping, and see more AR-15 accessories and parts while you are here.