SIG MCX LOWER for Sale
Browse SIG MCX Lower listings from verified sellers across the U.S. on GunsAmerica.
Quick Look
The SIG MCX platform was developed by SIG Sauer in the mid-2010s to provide modular, mission-adaptable rifles for military and law enforcement use. Its lower receiver features AR-style ergonomics while offering compatibility with unique MCX internal components. The SIG MCX lower is popular among shooters building customized rifles or converting existing uppers.
Why It's a Top Choice
- Compatible with SIG MCX upper receivers
- Non-buffer tube design allows folding stock
- AR-style control layout for intuitive use
- Fully ambidextrous selector and mag release
- High build quality and rugged construction
Key Variants
SIG MCX Spear LT Lower
The latest generation supporting AR-format triggers and lighter weight, ideal for civilian and LE builds.
SIG MCX Virtus Lower
Standout for its robust monolithic feel and compatibility with Virtus uppers for duty applications.
SIG MCX Rattler Lower
Designed for ultra-compact builds with folding stocks; ideal for PDW-style assembly.
Competitor Comparison Table
| Feature | Sig Mcx Lower | Daniel Defense Lower | BCM Lower |
|---|---|---|---|
| MSRP | $300–$500 | $200–$350 | $200–$350 |
| Capacity/Size | Standard AR mag well | Standard AR mag well | Standard AR mag well |
| Weight | ≈1.2 lbs (stripped) | ≈1.0 lbs | ≈1.0 lbs |
| Optics-Ready | Depends on upper | Depends on upper | Depends on upper |
| Trigger Type | AR-style drop-in | Mil-spec or drop-in | Mil-spec or drop-in |
| Notable Pro | Folding stock capability | Battle-proven reliability | Excellent aftermarket support |
| Notable Con | Limited upper compatibility | Requires buffer tube | Requires buffer tube |
Best Use Cases
- Custom MCX rifle builds
- Short-barreled PDW assembly
- Modern home defense configurations
- Suppressed rifle systems
- Collectors seeking factory-original lowers
FAQs
Can I use a standard AR-15 upper on a SIG MCX lower?
No, SIG MCX lowers are designed only for MCX-specific uppers due to internal differences.
What is the difference between SIG MCX Spear LT and Virtus lowers?
The Spear LT uses a lighter contour and AR-style triggers; Virtus lowers are heavier-duty for sustained use.
How does a SIG MCX lower enable a folding stock?
The MCX uses a recoil assembly housed within the upper, eliminating the need for a buffer tube.
Prefer nearby results? Toggle to search local listings.
SIG SAUER MCX VIRTUS 5.56 PISTOL 11.5"
$2,599.99
Sig Sauer MCX Rattler 5.56 5.5" SBR
$2,599.99
Sig Sauer MCX Rattler LT 7.62x39 7.75" P
$2,199.00
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