Sig MCX 9" SUR300 Suppressed Upper Receiver 300BLK

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  • Sig SUR300 Suppressed Upper Receiver 300blk
  • Sig MCX 9" SUR300 Suppressed Upper Receiver 300BLK
  • Sig SUR300 Suppressed Upper Receiver 300blk
MSRP: $2,640.00
— You save $261.00
Frequently bought together:


Sig Sauer's Suppressed Upper Reciever (SUR) in .300Blk is a complete MCX upper with bolt and charging handle included. Compatible with MCX and MCX VIRTUS systems, this upper is also compatible with most standard M4/AR-15 lower recievers. Sporting a 9 inch 300BLK barrel with a pinned and welded titanium suppressor, this upper comes in at a "barrel length" of 16.375" meaning that it does not require a SBR lower. This means that the SUR300 is a fantastic way to upgrade that old lower receiver you have laying around with the MCX VIRTUS piston operating system and a 2 position gas valve!

To that end, this upper ships with a MATCHLITE DUO two-stage match-grade drop in trigger as well as an AR 1913 receiver adapter for use with a folding stock. You really can't ask for a better package deal to upgrade an existing AR lower receiver!

Lastly, the silencer included with this upper receiver is proprietary to this system and is optimized for use on .300BLK.


  • Caliber: .300BLK
  • Receiver Material: 7075 Aluminum
  • Receiver Finish: Mil-Spec Type III Hard-Coat Anodize
  • Barrel Material: Cold Hammer-Forged Carbon Steel
  • Barrel Finish: Nitride
  • Barrel Length: 9"
  • Barrel Twist: 1:5in
  • Suppressor Material: Titanium
  • Suppressor Finish: Black DLC
  • Mount: Pinned and Welded
  • Weight 5.7lbs


  • QD Sling Adapter
  • M4/AR15 1913 Receiver Adapter and Folding Stock Adapter
  • Owners Manual
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Additional Information

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1 Review

  • 5
    Just in time

    Posted by 4Sig on 26th Feb 2020

    I was going to upgrade my somewhat 'old' lower. Looked at various options. Decided to give this dedicated suppressor setup a try.

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