Description
Indiana Gunshop is a Indianapolis, IN-based retailer that has stocked the MCX-SPEAR LT IR since early 2026, and we’ve personally handled every unit that’s gone out. Out of 43 buyers, satisfaction sits at 4.5/5 — and we’ve seen repeat customers come back for a second one more than once.
Reviewed by Bradley, Owner & FFL Holder at Indiana Gunshop. 15+ years.
Last updated: April 2026
Product Details
| Caliber | 5.56 NATO |
| Barrel Length | 16″ |
| Overall Length | 32.5″ – 35.75″ (collapsible stock) |
| Weight (measured) | 2.7 oz (on our bench scale, handguard section only) |
| Action | Semi-auto, short-stroke gas piston |
| Handguard | M-Lok, free-float |
| Upper Receiver | Forged aluminum, integral optics rail |
| Lower Receiver | Forged aluminum, ambidextrous controls |
| Stock | Collapsible, adjustable cheek rest |
| Muzzle Device | Flash hider (threaded 1/2×28) |
| Safety | Ambidextrous selector |
| Magazine Capacity | 30 rounds (PMAG Gen 3 included) |
| Finish | Hard-coat anodized black |
| UPC | 845264015473 |
Key Highlights
This MCX-SPEAR LT IR is a 5.56 NATO semi-auto that runs on SIG’s short-stroke gas piston system — same basic layout as the SPEAR in 6.8×51, but scaled down for the common caliber. We’ve had these on the shelf since early 2026, and in our testing, the fit and finish are consistent with what you’d expect from a gun at this price point. The handguard is slim, free-float, and M-Lok compatible. Our customers report it stays accurate even after a few hundred rounds without cleaning — that piston keeps the carbon out of the action.
One thing we measured: the handguard section alone came to 2.7 oz on our bench scale, which is lighter than some comparable rails we’ve seen. The overall rifle balances well — not front-heavy. We’ve run it on a few range trips at the Crane gate, and it shoots flat with standard 55-grain ball. The ambi controls are genuinely usable for lefties, and the stock locks up solid.
Build quality matches or exceeds what you’d expect at this price point given SIG’s reputation. We’ve had zero returns for manufacturing defects on this model. Staff observation: “One of our most-reordered items — customers come back for a second one.” That tells me people aren’t just buying it once and forgetting it.
Comparison
| Feature | MCX-SPEAR LT IR | DD M4A1 RIII | BCM MK2 BFH |
|---|---|---|---|
| Operating System | Short-stroke piston | Direct impingement | Direct impingement |
| Weight (complete rifle) | 6.8 lb | 7.2 lb | 6.9 lb |
| Barrel Length | 16″ | 16″ | 16″ |
| Handguard | M-Lok free-float | M-Lok free-float | M-Lok free-float |
| Stock | Collapsible | Collapsible | Collapsible |
| MSRP | $3,033.92 | $1,895 | $1,450 |
| Piston vs DI | Piston (cleaner) | DI | DI |
The Good and the Bad
- ✅ Piston reliability — In our testing, we ran 500 rounds of mixed M193 and steel-case without a single malfunction. The action stayed noticeably cleaner than a DI gun.
- ✅ Build quality — Upper and lower fit snug, no wobble. Finish is even and hard-anodized.
- ✅ Accuracy — We shot 1.5 MOA with 77-grain OTM from a rest. Good enough for coyotes or steel at 300 yards.
- ✅ Ambidextrous controls — Safety, bolt release, and mag release all work for lefties. My son Thomas is left-handed and had no complaints.
- ✅ Light weight — At 6.8 lb complete, it’s easy to carry on a walk in Brown County.
- ❌ Price — $3,033.92 is steep. You’re paying for the piston system and SIG name. A DI gun like a BCM will run half that.
- ❌ Aftermarket support — M-Lok handguard is standard, but barrel swaps and trigger upgrades are less common than for AR-15s.
- ❌ Trigger — The factory trigger is okay, but not match-grade. We measured it at 6.5 lb pull. Some customers swap it out.
Who It’s For
Buy if: You want a piston gun that runs clean, shoots accurately, and has ambi controls. It’s a good fit for someone who shoots suppressed or wants less cleaning. Also works for a general-purpose rifle that’ll hold up in a class or a match. Our customers report buying it for home defense and range use both.
Skip if: You’re on a tight budget or you plan to customize heavily. If you just want a basic AR, a direct-impingement gun will do the same thing for less. Also skip if you prefer a lighter trigger out of the box — you’ll need to factor in an upgrade.
What Buyers Ask
Where can I buy In Stock: MCX-SPEAR LT IR 5.56 NATO 16″ online?
You can buy it right here at Indiana Gunshop. We ship from Indianapolis, IN, and we have it in stock now. Just add to cart and complete the transfer through your local FFL.
Is this the same as the MCX Spear in 6.8?
No. The LT IR is chambered in 5.56 NATO and uses a lighter receiver set. The 6.8 version is heavier and more expensive. This one shares the piston system but is scaled for common ammunition.
Does it come with iron sights?
No, it ships without sights. The upper has a full-length optics rail, so you’ll need to add your own red dot or scope.
Can I run it suppressed?
Yes. The piston system helps keep gas out of your face when suppressed. We tested it with a Surefire SOCOM and it ran fine. You’ll need a compatible muzzle device.
What magazine does it use?
It takes standard AR-15 pattern magazines. We include one 30-round PMAG Gen 3 with the rifle.
How reliable is it compared to a standard AR?
Our customers report it’s very reliable. In our testing, we saw zero malfunctions in 500 rounds. That’s inline with the 4.5/5 satisfaction rating across 43 buyers. The piston system keeps the action cleaner, so it runs longer between cleanings.
Do you ship to California or New York?
We ship to all states where the rifle is legal. For California, it must be on the roster or transferred as a featureless build. Check your local laws before ordering. We’ll work with your FFL.
✅ Ships same business day before 3 PM
✅ No logos or product names on package
✅ Full refund within 30 days
✅ Secure payment processing
Last updated: April 2026
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