Breek Arms 3FO Outside Threaded Flash Hider for .300 Blackout – 5/8×24

SKU: BRK4058

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Breek Arms Blast Shield

Castle Blast Shield


.300 Blackout Flash Hider Readily Converted to Linear Compensator

For a.30 cal AR-15, having an effective flash hider is critical.  Having a flash hider that can can pull double-duty with a simple thread-on blast shield at a great price?  That’s something you’ll only get from Breek Arms.  The 3FO .300 Blackout Flash hider is a three-prong design, with an added feature of outside threading.  The threads are made to accept the Breek Arms Castle Blast Shield, which pushes propellant gases forward, reducing noise and concussion to the shooter.  Since .300 Blackout tends to have more punch coming from a short barrel, being able to choose between hiding flash and shooter comfort is a great option to have.  In the field, enjoy the benefits of the base flash hider, but for indoor trips, thread on the Blast Shield and save your ears.  Since they’re both available at a great price, you can’t really go wrong.

Includes 1 crush washer for easy timing and installation.  Does not include the Castle Blast Shield.


  • Intended Caliber: .300 Blackout
  • Muzzle Thread: 5/8 x 24 TPI
  • Outside Thread: 13/16 x 16 TPI
  • Material: Hardened 4140 Steel
  • Finish: Black Nitride
  • Comes with 1 Crush Washer
  • Overall length: 2.36″
  • Weight: 2.8 oz.
  • Length added to barrel: Approximately 1.7 inches
  • Prong length: 1.5″

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Customer Reviews

Based on 2 reviews
Marvin Stanford

Strong enough to thrust through chest cavity! Muzzle fair!

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Phil Rizzuto
I hate an A2

Revisited my first 300 bo build. Basic parts to learn to build. 8 in and pretty confident in my building now. Wanted to try something different and upgrade the upper. Havent actually gotten out to shoot this 1 yet but installed exactly as it should. Easy to time w/the crush washer. Looks great especially combined with the blast cover. Without firing it yet, I have no doubts itll function properly. Building a 2nd .300, id buy it again.

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