FFL-compliant checkout Live inventory verification Pickup / transfer ready
(800) 551-2791 beverlyhillsguns.com
0

Your cart is empty

Total $0.00
Sign In Create Account
Browse Beverly Hills Guns
Navigate by category, brand, and customer workflow.
Training, appointments, transfers, and company pages.
Store & Compliance
Built for modern storefront browsing without losing the firearm compliance workflow behind the scenes.
  • Live inventory validation before checkout
  • Workflow-aware store pickup and transfer routing
  • State-aware compliance filtering
  • Scoped category search that respects browse context
Search Beverly Hills Guns
Search by Manufacturer, Model, UPC, or MPN.
Sig Sauer MCX
California Proposition 65 Warning

This product can expose you to chemicals including lead, known to cause cancer and birth defects. For more info visit P65Warnings.ca.gov.

Sig Sauer

MCX

$1,799.99
Available California compliant

Sig Sauer MCX-Rattler LT, Complete Upper Receiver, 300 Blackout, 6.75" Threaded Barrel, 5/8X24 Thread Pitch, Fits AR-15 Lower Receivers, Anodized Finish, Black, Includes Charging Handle and Bolt Carrier Group, Clutch-Lok Tapered QD Flash Hider UAMCX-300B-6B-LT-BLK

Key Details
Brand Sig Sauer
Manufacturer Part Number UAMCX-300B-6B-LT-BLK
UPC 798681686896
SKU SGUAMCX-300B-6B-LT-BLK
Current Stock 31 available
Quantity Updated May 7, 2026 1:50 PM
Already have an account from an in-store purchase? Log in to use that profile for checkout and future orders.
Continue Shopping
Share This Product
Purchase Requirements
  • Final availability is confirmed at checkout.
In-Store Pickup Required: All firearm purchases must be picked up at our Beverly Hills location after background check completion.
Product Description

The MCX-RATTLER LT offers a 6.75" cold-hammer-forged barrel, compatibility with AR-style triggers, an adjustable gas system for suppressor optimization, a QD Clutchlok Muzzle Device, and an M4 adapter kit to convert any M4 lower to use the MCX platform's folding capability. The new MCX-RATTLER LT design is compatible with all MCX-SPEAR LT parts, so any barrel or handguard from the MCX-SPEAR LT can be interchanged, enabling easy caliber and length conversions. Advanced beyond any platform in its class, the MCX-RATTLER LT upper is the ultimate upgrade for your MCX or M4 lower.

Features
  • Adapts with Any M4/AR15 Spec Lower Assembly
  • Dual Rod Recoil Assembly Eliminates Buffer System
  • Adjustable Gas System
  • Quick Change Barrel Design
  • Ambidextrous Charging Handle with Gas Deflector
  • Tapered Bolt Design
  • Compatible with SLX/SLH Suppressors
Specifications
UPC: 798681686896
Manufacturer: Sig Sauer
Manufacturer Part #: UAMCX-300B-6B-LT-BLK
Model: MCX
Model (Alt): Rattler LT
Barrel Length: 6.75"
Capacity: N/A
Finish: Anodized
Sights: Flat Top
Type: Upper