First Look: SIG Sauer MCX Rattler LT .300BLK Upper

A 6.5 inch barrel means it's easy to handle in tight spaces.

by
posted on May 18, 2024
SIG Sauer MCX Rattler LT .300BLK Uppe

SIG Sauer is now offering a new short-barrel upper-receiver assembly chambered in .300BLK for the MCX Rattler LT series of short-barrel rifles and large-format pistols. This drop-in upper works with any MCX Rattler LT lower receivers and offers users the chance to fire the popular .300BLK cartridge through their existing SIG Sauer MCX Rattler LT firearm with a shorter, 6.75-inch-long, suppressor-ready barrel. These upper receiver groups also make use of adjustable gas systems to adjust for their shorter barrels and to work efficiently with suppressors.   

SIG Sauer MCX Rattler LT Features:

  • Adapts with any M4/AR15 spec lower assembly
  • Dual-rod recoil assembly eliminates buffer system
  • M4 adapter allows for Picatinny rail folding stock
  • Adjustable gas system for suppressor optimization
  • Quick-change barrel design allows to easily swap calibers and barrel lengths
  • Gas piston reduces part exposure to carbon fouling
  • Built to fire 20,000 rounds before any part replacements
  • SLX/SLH Next Gen Suppressor QD Flash Hider for Clutch-Lok adaptability
  • Ambidextrous charging handle with gas deflector
  • Replaceable parts (cam path follower, feed ramp, forward assist/deflector, charging handle locking pins) allow for longer receiver life over standard AR designs
  • Tapered bolt functions more reliably and lasts longer than standard square lug M4 bolt
  • Nitride coated cold hammer forged barrel for optimal accuracy and barrel life

The SIG Sauer MCX was introduced and became the choice of Special Forces groups worldwide. The platform offered a replacement to pistol-caliber platforms with superior ballistics and first-rate subsonic performance thanks to use of subsonic .300BLK ammunition. The MCX-Rattler LT upper assembly offers the same design that changed a generation of rifles with updated features that reflect the needs of today’s gun owner. To learn more about this new upper receiver or other products from SIG Sauer, visit sigsauer.com.

Latest

SK Customs Lost State of Montezuma 1911
SK Customs Lost State of Montezuma 1911

First Look: SK Customs Lost State of Montezuma 1911

A custom pistol to commemorate a pivotal moment in American history.

First Look: Hawke Optics Frontier Reflex Sight

Available with three different mounting options.

Bond Arms Celebrates 30th Anniversary

Once known just for derringers, the company continues to diversify.

Handguns: Massive Bore

Big-bore carry guns are trending larger now, although Charter Arms’ compact Bulldog remains in production.

First Look: State-Compliant Kimber 2K11 Pistols

For those who live in capacity-restricted states.

NRA Annual Meeting 2025 Exhibition Floor Roundup

What we saw on the show floor in Atlanta.

Interests



Get the best of Shooting Illustrated delivered to your inbox.