Sig Sauer MCX Spear LT 5.56 NATO
Model: RMCX-556N-16B-LT-B
Sig Sauer MCX Spear LT 5.56 NATO
Model: RMCX-556N-16B-LT-B
Full Specifications
Threaded 1/2x28 barrel: compare 5.56 / .223 suppressor prices.
About This Firearm
The Sig Sauer MCX Spear LT is a short-stroke piston semi-automatic 5.56 NATO built for duty and defensive use. It has an MSRP of $2,619.99. Its muzzle device is a quick-detach suppressor-ready flash hider set with Rocksett, so a Sig suppressor clamps onto the device itself and the 1/2x28 tapered-shoulder thread underneath takes anything else.
One 30-round polymer magazine comes with it. The stock folds, which brings the rifle to 34.3 inches with the 16-inch barrel still in place, and the gas system is adjustable, so it can be turned down behind a suppressor. Every control works from either side and the trigger is a flat two-stage Matchlite Duo. No sights are fitted. The barrels are interchangeable without a gunsmith.
If you're cross-shopping, a Daniel Defense DDM4 V7 has an MSRP of $2,073, uses direct impingement behind a fixed receiver extension and carries 1.20 lbs less. An HK MR556A1 has an MSRP of $3,499 and is the other short-stroke piston rifle here, heavier again by the same margin, with no folding stock and no barrel swap. The Spear LT sits between the two on weight, and neither of the others has a folding stock.
Best For
Strengths & Limitations
- A forward assist is fitted.
- The muzzle device is set with Rocksett, so it stays put under suppressor use instead of backing off.
- Sig's Infinite Guarantee needs no receipt and no warranty card, and it goes with the rifle to its next owner.
- No sights are included, so flip-ups on the rail are the backup if the optic takes a knock.
- A piston and a folding joint both add weight over a direct-impingement carbine of the same barrel length.
Category Rankings
How the Sig Sauer MCX Spear LT 5.56 NATO ranks among full-size 5.56 NATO rifles.
Compatible Ammunition
Find the best prices on compatible 5.56 NATO ammunition.
Shop 5.56 NATO Ammo →Ballistics Calculator
Calculate trajectory, drop, and energy for 5.56 NATO ammunition.
5.56 NATO Ballistics →Alternatives to Consider
Similar full-size 5.56 NATO rifles ranked by similarity.
| NAME | BEST PRICE |
|---|---|
|
CZ Bren 2 Ms Carbine 5.56 NATO
CZ
|
$2,403.99 |
|
Daniel Defense DDM4 V7 Pro 5.56 NATO
Daniel Defense
|
— |
|
Anderson AM-15 5.56 NATO
Anderson
|
— |
|
Palmetto State Armory PA-15 5.56 NATO
Palmetto State Armory
|
— |
|
FN 15 TAC3 5.56 NATO
FN America
|
$1,699.99 |
Frequently Asked Questions
How does it differ from the MCX Virtus it replaced?
Sig describes the Spear LT as built on the Virtus's legacy with a lightened handguard, a match trigger, fully ambidextrous controls, interchangeable barrels and the Rocksett-set quick-detach flash hider.
Does a folding stock change its legal status?
No. The barrel is 16 inches, past the short-barreled rifle threshold, and folding the stock does not change that.
What magazines does it take?
Standard AR-15 magazines. Sig lists the magazine type as AR-15 and supplies one polymer magazine with the rifle.
