Brownells Ar-15 Modular Gas Block, 0.750''

The Brownells AR-15 modular gas block is built for shooters who want a free-floating barrel setup without sacrificing the ability to mount tactical accessories. Unlike fixed gas blocks that limit your configuration options, this 0.750" block ships with an integral Picatinny rail on top and allows you to add up to three more rails on the sides and bottom—giving you the flexibility to run lasers, weapon lights, backup sights, night vision optics, or whatever your mission demands. Swap rails in and out with just two screws per rail, so you can reconfigure your setup between range sessions, competitions, or field work without swapping the whole block.

Precision-machined from 6061 billet aluminum, the gas block is strong enough for hard use while keeping weight minimal—a real consideration on a lightweight AR build. Three hardened steel setscrews lock the block securely to your barrel, and the integral top rail eliminates the need for a separate accessory rail if you're mounting something forward. Installation is straightforward: clamp it on, tighten the three setscrews, and you're ready to run optics or accessories on the rail system you've chosen.

This is a solid choice for AR builders who want modularity without proprietary or quick-detach rail systems, and for anyone running a free-floated barrel who still needs a stable platform for mounted gear. Whether you're setting up for precision rifle, tactical drills, or practical shooting, the modular design adapts to your needs.

Key Features

• Integral top Picatinny rail with support for up to three additional modular rails
• Modular side and bottom rails attach with two screws each for quick reconfiguration
• 6061 billet aluminum construction balances strength and weight
• Three hardened steel setscrews secure the block to your 0.750" barrel
• Accepts lasers, lights, night vision optics, backup sights, and other tactical accessories

Specifications

Frequently Asked Questions

What size barrel does this gas block fit?

This block is sized for a 0.750" barrel profile, which is standard on most modern AR-15 builds. Verify your barrel diameter before ordering.

Can I mount accessories directly to this gas block?

Yes. The gas block comes with an integral Picatinny rail on top that accepts any standard Picatinny-mounted accessory. You can also add up to three modular rails on the sides and bottom to expand your options.

How do I attach and remove the modular rails?

Each modular rail (side and bottom) fastens with two screws. You can add or remove them without tools beyond a screwdriver, making it easy to reconfigure your setup as needed.

Is this gas block compatible with free-floating barrels?

Yes, this is a clamp-on design that works with free-floated barrels. The three setscrews clamp the block to the barrel without interfering with barrel vibration or accuracy.