We recently got some exclusive test time with Sig Sauer’s latest rifle: The MCX Rattler.

It is one of, if not the shortest, AR platform rifles available to date with a sub-6-inch barrel. Designed as a compact close quarters rifle, it packs a punch. The MCX operating system allows firing while folded. Its stock provides access to all controls.

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Available as an SBR, it will be available as an upper for any MCX lower. A proprietary gas block allows use in 300 BLK suppressed and unsuppressed, with both super and subsonic ammunition. A 5.56mm version will be available for unsuppressed fire only.

“Built for top-tier units, the short-stroke piston design eliminates the bugger tube, yet maintains familiar M4 controls,” according to Sig.

Spending time on the range with the MCX Rattler, mine was tested with both super and subsonic loads unsuppressed and it ran everything well. Accuracy was excellent at 50 yards on 4-inch round plates. Some full-auto time using 125 grain FMJ full power ammunition quickly explained the “rattler” moniker. It was a handful and some serious fun!

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Scroll through the gallery above and be sure to watch the quick video below to see the MCX Rattler in action.

For more on the Rattler and other products from Sig, please visit

MCX Rattler Specifications

  • Caliber: 300 BLK
  • Frame Material: 7075 T6 aluminum
  • Frame Finish: Anodized
  • Barrel Material: Carbon steel
  • Barrel Finish: Nitride
  • Sights: Optics ready
  • Trigger: SIG Enhanced
  • Overall Height: 8 inches
  • Overall Width: 2.8 inches
  • Barrel Length: 5.5 inches
  • Barrel Twist: 1:5 inches
  • Overall Length: 19.3 inches
  • Weight with Magazine: 5.1 pounds
  • Trigger pull: 5.5-9 pounds
  • MSRP: $2,727 (SBR model)

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