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CMMG 12.5" .300 BLK Pistol-Length Multi-Role Barrel (CMMG30D8A0A) on a AR-15

AI illustration of a similar part on the gun.

AR-15 · Barrel

CMMG 12.5" .300 BLK Pistol-Length Multi-Role Barrel (CMMG30D8A0A)

$180

Under 16 in: a rifle needs a pinned and welded muzzle device to reach 16 in overall barrel length, or NFA registration as an SBR.

Build with this part

Opens the builder with this part fitted. Other parts change only if they have to.

Specs

Length (in)12.5
Caliber300
Calname.300 Blackout
Gas systempistol
Thread5/8x24

Pros and cons

Pros
  • Pistol gas at 12.5 in runs subs well
  • 1:7 twist for heavy subsonic bullets
  • Nitride finish inside and out
Cons
  • 4140 steel, not 4150
  • Needs a 3.5 in device pinned and welded for a 16 in rifle

Other barrel options