Maxim Defense SDX RFLX SBR, .300 Blackout, 8.5-Inch, Black

The Maxim Defense SDX RFLX (brand part no. MXM-49222) is a .300 AAC Blackout short-barrel rifle finished in black, representing a new evolution in integrally suppressed weapon systems from Maxim Defense. Maxim Defense builds the SDX RFLX on the battle-proven SDX platform with an M-Kore reflex suppressor, a true over-the-barrel system that reduces added length while maximizing sound reduction and balance, paired with a tuned gas system. The SDX RFLX favors shooters who want an integrally suppressed .300 Blackout SBR.

Key Specifications

• Chambered in .300 AAC Blackout.
• Wears an 8.5-inch barrel.
• Feeds from a 30-round magazine.
• Built with Maxim’s M-Kore reflex suppressor over-the-barrel system.
• Finished in black.

Frequently Asked Questions

Is this an NFA item? Yes. As a SBR, it’s a Title II firearm requiring an approved ATF Form 4 and transfer through an NFA-licensed dealer.

What caliber does it fire? .300 AAC Blackout.

How does it mount? Maxim’s M-Kore reflex system, an over-the-barrel design secured with an adapter ring lock and tuned specifically to this platform — it is fully user-serviceable and disassembles with common tools.

Buy the Maxim Defense SDX RFLX SBR

This is a Title II item regulated under the National Firearms Act. Purchase requires an approved ATF Form 4, no federal transfer tax, and transfer through a licensed NFA (SOT/Class 3) dealer, with an extended federal approval wait before delivery. Order through Maxim Defense‘s short barrel rifles lineup and our Lubbock, Texas team will walk you through the transfer process.