SIG Sauer MCX
Piston-driven carbine · Caliber-swap upper · Suppressed .300 Blackout
| Manufacturer | SIG Sauer |
|---|---|
| Category | Rifles |
| Caliber | .300 Blackout / 5.56 NATO |
| Action | Semi-automatic (short-stroke gas piston) |
| Barrel length | 16.0 in |
| Capacity | 30+1 |
| Weight | 8.6 lb |
| Introduced | 2015 |
About the SIG Sauer MCX
The MCX replaces the direct-impingement path with a short-stroke gas piston that keeps fouling out of the receiver, and the platform was designed from the start to run both 5.56 NATO and .300 Blackout on the same lower. That modularity lets a shooter change caliber by swapping the upper assembly rather than rebuilding the rifle. The free-floated handguard accepts accessories along its length, the folding stock shortens the rifle for transport, and the piston system runs cooler during extended strings than a comparable direct-impingement gun.
Best ammo for the SIG Sauer MCX
Live picks from Top Ammo Supply — in-stock .300 Blackout and 5.56 NATO ammunition, sorted by price per round. Prices and stock refresh throughout the day.
.300 Blackout defensive loads
Hollow points tested for duty and self-defense use.
BarnesBarnes 300 AAC Blackout AMMO 125gr OTM BT 20rd Box 20rd$37.79$1.889/rdFull selection: Browse all .300 Blackout ammunition at Top Ammo Supply →
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