Sig Sauer MCX and Spear
The MCX is Sig's gas piston rifle family. It runs without a buffer tube, so many versions take folding stocks or come as very short guns. We stock the MCX Spear built around 277 Fury, the lighter Spear LT, the short Rattler and other MCX rifles and pistols.Sig's gas piston rifle family: the Spear, the Spear LT and the short Rattler, side by side.
Prices from $2,267.00 to $4,199.99, as of Nov 13, 2026.
Pick your MCX
Every MCX line we list, with the count in stock and the lowest price for each.
All MCX guns
14 in stock. Sold out listings stay up, after the ones you can buy today.
Compare MCX models
The most listed size for each model in stock. 10 round versions of most models are listed for states with magazine limits.
As of Nov 13, 2026
Compare MCX models
The most listed size for each model in stock. 10 round versions of most models are listed for states with magazine limits.
| Model | Size / grip | Barrel | Standard mag | Calibers | In stock | From | Shop |
|---|---|---|---|---|---|---|---|
| Spear LT | 16 in | 28 or 30 | 7.62x39mm, 5.56 NATO | 7 | $2,267.00 | Shop | |
| Spear | 13 or 16 in | 20 | 7.62x51mm NATO, 277 Fury | 5 | $3,999.99 | Shop | |
| Rattler | 5.5 in | 30 | 5.56 NATO | 1 | $2,499.99 | Shop | |
| MCX | 16 in | 30 | 5.56 NATO | 1 | $2,267.00 | Shop |
Source: barrel, magazine and caliber are taken from our in-stock listings for each model.
Built for your MCX
Magazines, scope mounts and parts that fit the MCX, from Sig and other makers. Parts ship to your door where your state allows.
What makes the MCX different
Most AR-15s are direct impingement: gas from the barrel runs back into the action. The MCX uses a short stroke gas piston instead, which keeps more of that gas and heat out of the action. Its recoil system sits in the upper receiver, so it does not need a buffer tube behind the receiver. That is why many MCX versions take folding stocks, and why the shortest ones can be so compact. The 5.56 NATO and 300 Blackout models take standard AR-15 magazines.
MCX models
The Spear LT is the lighter MCX for 5.56 NATO, 300 Blackout and 7.62x39. Our Spear LT listings come with barrels from 9 to 16 inches, as rifles, short barrel rifles and pistols. The Rattler is the compact MCX, with 5.5 to 7.75 inch barrels in our listings. The Virtus is the earlier MCX generation, and we list it as a rifle and a pistol. We have 7 Spear LT, 5 Spear and 1 Rattler listings in stock.
MCX Spear and the XM7
In 2022 the U.S. Army picked Sig's rifle for its Next Generation Squad Weapon program, where it is called the XM7. The MCX Spear is the civilian version. Sig built it around 277 Fury, its commercial name for the 6.8x51 cartridge, and our listings also show Spear versions in 7.62x51 NATO and 6.5 Creedmoor. Pair it with 277 Sig Fury ammo or browse Sig ammo.
Calibers
Right now we stock 5 in 5.56 NATO, 4 in 7.62x39mm, 3 in 7.62x51mm NATO and 2 in 277 Fury. 300 Blackout was designed to work well from short barrels and with suppressors, so it shows up on many short MCX models, while 5.56 NATO is common on the longer rifles. Shop 300 Blackout ammo, 5.56 NATO ammo and 308 Winchester ammo.
Buying a rifle online
Short barrel rifles and braced pistols can have extra rules in some states, so read each listing and check our state restrictions page first.
Magazines, stocks and parts ship to your door where your state allows. Check state restrictions before you order, and read how buying a gun online works. Firearms can go on layaway, and financing shows at checkout when the order qualifies.
More Sig Sauer series
Sig MCX FAQ
What is the difference between the MCX, the Spear LT and the Spear?
The MCX is Sig's gas piston rifle family. The Spear LT is a lighter MCX for 5.56 NATO, 300 Blackout and 7.62x39. The MCX Spear is the bigger rifle built around 277 Fury, the civilian version of the rifle the U.S. Army calls the XM7.
Does the MCX use AR-15 magazines?
The 5.56 NATO and 300 Blackout models take standard AR-15 magazines. The 7.62x39 and 277 Fury models take magazines made for their cartridge, and our 7.62x39 listings hold 28 rounds. Check each listing.
Can the MCX stock fold?
The MCX does not need a buffer tube, so many versions take folding stocks, and several of our listings come with one. Check each listing for the stock or brace it ships with.
What is the MCX Rattler?
The compact MCX, with 5.5 to 7.75 inch barrels in our listings, in 300 Blackout, 5.56 NATO and 7.62x39. Depending on the version it is a pistol, a pistol with a brace or a short barrel rifle.
What caliber is the MCX Spear?
Sig built the Spear around 277 Fury, its name for the 6.8x51 cartridge. Our listings also show Spear versions in 7.62x51 NATO and 6.5 Creedmoor. Shop 277 Sig Fury ammo.
Do you carry Sig suppressors for the MCX?
Yes. Our Sig suppressors page lists the cans and mounts we stock, including a quick disconnect model listed for 6.8x51.
Do you ship MCX rifles to my house?
No. Rifles, pistols and short barrel rifles ship to a licensed dealer (FFL) you pick at checkout. Short barrel rifles and braced pistols can have extra rules in some states, so check our state restrictions page before you order.