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AR-15Mid-Range

CMMG

CMMG Banshee Mk4 SBR (8" .300 Blackout)

Sub-$1,500 factory .300 BLK SBR with 8" pistol-length gas system tuned for sub/supersonic cycling.

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Key Highlights

  • Sub-$1,500 factory .300 BLK SBR — the budget tier reference for suppressor hosts
  • Optimized 8" gas system runs subsonic and supersonic .300 BLK without an adjustable block
  • Salt-bath-nitrided 4140CM barrel — corrosion resistance and accuracy match CMMG's price floor

Specifications

Price
$1,449
Weight
5 lb 8 oz
Calibers
.300 AAC Blackout
Rail Type
mlok

Capability Profile

0-10 Scale Across 8 Axes

Compatibility Tags

family: modern-riflefamily: ar-patterntrigger: ar-fcginterface: picatinny-tophandguard: mlokbarrel: ultra-compactthread: 5/8x24mag-type: stanag

Overview

The CMMG Banshee Mk4 SBR in 8" .300 Blackout is the cheapest factory .300 BLK short-barreled rifle with a real warranty pipeline behind it. CMMG's pistol-length gas system on the 8-inch barrel is the entire reason this platform exists: it's tuned at the factory to cycle both subsonic 220-grain suppressed loads and supersonic 110-125 grain defensive ammo without an adjustable gas block. That single engineering choice puts it in direct competition with $2,500+ piston guns from Sig and Q for the suppressor-host role, at roughly half the price.

The 8" 4140CM barrel runs a salt-bath nitride finish — internal and external corrosion resistance on par with chrome lining at a lower weight penalty. CMMG threads the muzzle 5/8x24, which is the correct .30-caliber standard and accepts any direct-thread or QD .30-cal suppressor without an adapter. The RML7 M-LOK 7-inch handguard floats the barrel and gives a clean accessory layout for a light and a sling mount; the skeletonized lower trims weight to ~5.5 lbs total, which rivals premium .300 BLK SBRs that cost two to three times as much.

The Banshee Mk4 is sold as a Form 4 SBR with a real stock, not a brace. The federal making/transfer tax on suppressors and SBRs was zeroed under OBBBA effective 2026-01-01, but registration, fingerprints, and NICS still apply — Form 4 wait times on the eForm pipeline are running days to a couple of weeks. Stock trigger is functional rather than match-grade and 8" supersonic .300 BLK falls off past 100 yards, but neither limitation matters for the role this rifle is built for: a suppressed, sub-6-pound house gun or truck gun where the suppressor and the ammo, not the barrel, do the work.

Key Features

  • 8" medium-taper 4140CM barrel, salt-bath nitrided, 1:7 twist
  • Pistol-length gas system tuned for subsonic and supersonic .300 BLK
  • 5/8x24 threaded muzzle accepts standard .30-cal direct-thread and QD suppressors
  • CMMG RML7 M-LOK 7" free-float handguard
  • Skeletonized billet lower receiver for weight reduction
  • AR-15 mil-spec fire control group and standard charging handle
  • ~24.5" overall length with stock collapsed
  • 5.5 lb total weight with stock

Pros

  • +Cheapest factory .300 BLK SBR with a real warranty and QC pipeline
  • +Skeletonized lower and 5.5 lb total weight rivals premium .300 BLK SBRs
  • +5/8x24 threaded muzzle accepts any standard .30-caliber direct-thread or QD suppressor
  • +Pistol-length gas tuned at the factory for both subsonic and supersonic cycling

Cons

  • NFA item — Form 4 transfer + ATF registration paperwork (federal tax zeroed under OBBBA effective 2026-01-01)
  • Stock CMMG trigger is functional, not match-grade
  • 8" barrel limits supersonic .300 BLK effectiveness past ~100 yards
  • M-LOK rail length (7") limits long-handguard accessory layouts

Detailed Specifications

caliber
.300 AAC Blackout
Barrel Length
8 inches
Overall Length
~24.5 inches (stock collapsed)
weight
5.5 lbs
Gas System
pistol-length
Twist Rate
1:7
barrel
4140CM steel, medium taper, salt-bath nitrided
handguard
CMMG RML7 M-LOK free-float, 7-inch
trigger
Mil-spec AR-15 single-stage
stock
Collapsible AR stock (NFA SBR configuration)
muzzleThread
5/8x24
msrp
$1,449.95

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