Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New
SIG Sauer MCX SPEAR-LT Complete Pistol Lower Receiver, Factory New
So you want to build a serious MCX SPEAR-LT pistol without tracking down individual parts. This lower gets you there. A factory new SIG Sauer MCX SPEAR-LT complete pistol lower receiver. Fully ambidextrous controls. No buffer tube. Coyote brown anodized finish. FFL transfer required.
This is genuine SIG factory production, not an aftermarket clone. First, the MCX SPEAR-LT lower eliminates the traditional buffer tube entirely, since the recoil system lives in the upper. Next, that means you can run a folding stock using the integrated Picatinny stock adapter rail. Finally, this ships complete with the minimalist stock, factory manual, and lock.
Is this lower a complete firearm requiring FFL transfer?
Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New Yes. So this is a serialized receiver, legally considered a firearm. Therefore, it ships only to your licensed FFL dealer. Also, federal law requires buyers to be 21 or older to purchase a stripped or complete receiver. Therefore, confirm with your FFL before ordering.
Will this Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New work with a standard AR-15 upper?
Yes, specifically for some MCX SPEAR-LT uppers. So SIG designed the SPEAR-LT lower to accept standard AR-15 style triggers, which is a key advantage over earlier MCX lowers. Also, the 7.62x39mm SPEAR-LT upper is confirmed compatible with a standard AR-15 lower as well. However, for the full folding stock benefit, you’ll want to run it with an MCX upper since the recoil system lives there.
What calibers can I build on this lower?
Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New Multiple options across the MCX SPEAR-LT upper lineup. So SIG offers SPEAR-LT pistol uppers in 5.56 NATO and 7.62x39mm, both with 11.5 inch barrels. Also, a .300 Blackout pistol configuration is available with a 9 inch barrel. Therefore, this lower gives you a foundation that works across the entire SPEAR-LT pistol caliber lineup by swapping uppers.
Why does having no buffer tube matter?
Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New It unlocks true folding stock capability. So traditional AR-15 pattern rifles require a buffer tube extending behind the lower, which physically prevents a true folding stock. Also, the MCX SPEAR-LT’s recoil system is fully contained in the upper receiver. Therefore, this lower can accept a folding stock directly via its integrated Picatinny rail, giving you a genuinely compact folded profile you can’t achieve on a standard AR lower.
Who is this Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New best for?
This Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New fits MCX SPEAR-LT builders who want factory SIG engineering on their lower while sourcing or swapping uppers separately. So if you already have or are sourcing an MCX SPEAR-LT upper, this gives you the correct, matched lower with genuine SIG ambidextrous controls and no-buffer-tube architecture. Also good for shooters specifically wanting the folding stock advantage in a pistol configuration.
Specs Table
| Spec | Detail |
|---|---|
| Receiver Status | Serialized firearm; must be 21+ to purchase |
| Platform | SIG MCX SPEAR-LT |
| Configuration | Pistol lower receiver |
| Compatible Calibers | 5.56 NATO, 7.62x39mm (11.5″ barrel); .300 Blackout (9″ barrel) |
| Controls | Fully ambidextrous (bolt catch, bolt release, safety) |
| Buffer System | None — recoil system housed in upper receiver |
| Stock Interface | 1913 3-slot Picatinny rail (rear) for folding stock adapters |
| QD Points | Rear QD sling point |
| Finish | Coyote brown anodized |
| Includes | Complete lower, minimalist stock, factory manual, lock |
| Trigger Compatibility | AR-15 style triggers |
| Manufacturer | SIG Sauer, factory new |
| Best For | MCX SPEAR-LT pistol builds, folding stock configurations, modular builds |
| Weight | verify |
| Price | $700 |
FAQ
Is this lower a complete firearm requiring FFL transfer? Yes. It’s a serialized receiver. FFL transfer required, and buyers must be 21 or older.
Will this Sig Sauer MCX SPEAR-LT Complete Pistol Lower Receiver Factory New fit a standard AR-15 upper? Not directly for most configurations. This is designed for MCX SPEAR-LT uppers. However, AR-15 style triggers are compatible.
Does this lower need a buffer tube? No. The MCX SPEAR-LT recoil system lives entirely in the upper receiver, eliminating the buffer tube and enabling folding stocks.
What calibers can I run on this lower? 5.56 NATO and 7.62x39mm with 11.5″ pistol uppers, or .300 Blackout with a 9″ pistol upper.
Does this lower include a stock? Yes. The minimalist folding stock ships with this complete lower.
Are the controls ambidextrous? Yes. Bolt catch, bolt release, and safety selector are all fully ambidextrous.
Can I use any AR-15 trigger in this lower? Yes. The MCX SPEAR-LT lower accepts standard AR-15 style triggers, unlike earlier MCX lowers that required proprietary triggers.
Find more SIG Sauer MCX SPEAR-LT components and pistol lower receivers at gunpartspalace.com.
