Breek Arms BRK4421 Sentinel Caged Plan B Black Nitride Steel 5/8"x24 Threads 30 Cal

The Breek Arms Sentinel is a closed-tine flash hider built for shooters running Plan B suppressor mounts or planning a pin-and-weld build on a 14.5" barrel. This 30 caliber muzzle device combines a fully shrouded design with practical, field-friendly engineering: it suppresses muzzle flash effectively, keeps snagging on gear to a minimum, and maintains a low signature under night vision. Whether you're setting up a precision rifle or a home-defense carbine that needs to meet legal barrel length requirements, the Sentinel delivers the alignment and durability you need without the fuss.

The Sentinel is machined from 4140 hardened steel and finished in black nitride for corrosion resistance and a clean aesthetic. Its compact footprint—just 2.15 inches overall—doesn't add bulk to your setup, and at 1.8 ounces it won't throw off your balance. The 5/8x24 thread pitch is the standard for .30 caliber rifles, making compatibility straightforward. The closed-tine, fully shrouded construction means no exposed prongs to catch on slings, chest rigs, or barricades, a real advantage in the field or on the move.

This is purpose-built hardware for the shooter who wants flash control, mounting simplicity, and zero compromise on ruggedness. If you're committed to a Plan B mount or a pin-and-weld configuration, the Sentinel gives you all the performance and precision Breek Arms is known for.

Key Features

• Closed-tine, fully shrouded design for superior flash suppression
• Purpose-engineered for Plan B suppressor mounts and pin-and-weld applications
• Low-profile, NVG-friendly signature reduction
• Minimal snag profile—no exposed prongs to catch gear
• 4140 hardened steel with black nitride finish for durability and corrosion resistance
• Rock-solid alignment and compact overall length

Specifications

Frequently Asked Questions

Is the Sentinel compatible with Plan B suppressor mounts?

Yes. The Sentinel is engineered specifically for Plan B suppressor mounts and integrates seamlessly with that system.

Can I pin and weld the Sentinel to a 14.5" barrel?

Yes. The Sentinel is designed for pin-and-weld builds on 14.5" barrels, allowing you to meet the 16" federal minimum barrel length requirement.

What thread pitch does the Sentinel use?

The Sentinel is threaded 5/8x24 TPI, the standard for .30 caliber rifles.

Will the closed-tine design snag on gear?

No. The fully shrouded, closed-tine construction eliminates exposed prongs, so it won't catch on slings, rigs, or barricades in the field.