SKU: CMMG30D120A
UPC: 815835016238
The CMMG Barrel 300 Blackout 16.1" Mount 4140 Chrome Moly is a pre-assembled barrel sub-assembly purpose-built for 300 Blackout AR15 upper builds. Properly headspaced and fitted with an M4 barrel extension, this barrel arrives ready for integration into a custom receiver, eliminating the need for barrel installation and timing—critical advantages for builders who want to minimize assembly error and get into the field faster.
The 4140 chrome moly construction provides established durability across thermal cycling and sustained-fire scenarios common to both suppressed and unsuppressed use. A 1:7 twist rate stabilizes the full range of 300 Blackout ammunition, from lightweight supersonic loads to heavy subsonic rounds—a critical specification when operating across variable ammunition types. The medium taper profile balances weight savings with rigidity, while the carbine-length gas port (.750" gas block journal) and 5/8x24 thread pitch enable reliable cycling and straightforward suppressor or muzzle device attachment. The 16.1" length sits in the sweet spot for 300 Blackout performance: long enough to extract meaningful velocity gains over shorter barrels, short enough to maintain handling advantages in close-quarters or vehicle-based work.
This barrel assembly suits operators building dedicated 300 Blackout uppers for suppressed duty, home defense platforms, or specialized training carbines. The pre-installed extension and headspace verification reduce build complexity and give builders confidence that function-critical tolerances are factory-correct. Buyers integrating this into a complete upper should verify lower receiver compatibility and confirm that their bolt carrier group and magazines support 300 Blackout ammunition.
The 300 Blackout platform remains a mainstay among tactical professionals and serious enthusiasts working with suppressed systems, where its subsonic ballistics and hearing-safe performance in short-barreled configurations deliver genuine operational value. This CMMG barrel delivers the core ballistic platform without the assembly overhead.
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