CMMG115745474
CMMG BANSHEE MK4 5.56x45 12.5" Upper Group - Black$841.04
Availability: In Stock
Current Stock: Out of stock
The CMMG BANSHEE MK4 5.56x45 10.5" upper group is purpose-built for shooters who prioritize compact size and lightweight handling without sacrificing reliability. At just 10.5 inches, this is CMMG's shortest 5.56mm upper offering—ideal for those building an ultra-compact AR15 that moves fast in tight quarters, fits easily in a vehicle, or simply feels right in your hands. Whether you're assembling a truck gun, a home-defense carbine, or a nimble range build, this upper delivers the firepower of 5.56 in a footprint that goes places bigger rifles can't.
Everything arrives ready to run: the upper comes complete with bolt carrier group, polymer dust cover, ambidextrous charging handle, and CMMG's ZEROED linear compensator. The billet 6061-T6 aluminum upper receiver pairs with an EML9 M-LOK handguard, giving you modern mounting flexibility without excessive weight. The 4140CM barrel features a 1:7 twist and carbine-length gas port, tuned for reliable operation in a short, direct-impingement system with a fixed 0.750" non-adjustable gas block.
At 3.5 pounds and 18.8 inches overall, the BANSHEE MK4 upper prioritizes portability and balance. The muzzle threads at 1/2x28 accept standard suppressors or brakes, and the linear compensator included here helps tame recoil and noise in close-quarters scenarios. The Mk4 platform is a proven CMMG design that keeps the short-barrel concept simple and functional—no exotic systems, just clean engineering that hunters, shooters, and outdoor enthusiasts have relied on.
This is a versatile upper for builders and tinkerers who want precision parts without the guesswork. Pair it with your favorite lower, zero in, and you've got a rifle that handles like a pistol but delivers rifle performance.
| Brand | CMMG |
| Platform | Mk4 AR15 |
| Caliber | 5.56x45mm (.223 Remington) |
| Barrel Length | 10.5" |
| Barrel Twist Rate | 1:7 |
| Barrel Material | 4140CM |
| Barrel Contour | MR |
| Operating System | Direct Impingement |
| Gas Block | 0.750" non-adjustable |
| Gas Port Location | Carbine length |
| Upper Receiver | Billet 6061 T6 aluminum |
| Handguard | CMMG EML9 M-LOK |
| Charging Handle | CMMG ZEROED ambidextrous |
| Muzzle Device | CMMG ZEROED linear compensator |
| Muzzle Thread | 1/2 x 28 |
| Includes | Bolt carrier group, dust cover, charging handle, linear compensator |
| Weight | 3.5 lbs |
| Overall Length | 18.8" |
| Finish | Cerakote (Black) |
The CMMG BANSHEE MK4 upper is built on CMMG's Mk4 AR15 platform and will mate with any standard AR15 lower receiver that accepts a Mk4 upper.
This is an upper group assembly, so you'll need to pair it with an AR15 lower receiver to complete a functional rifle. The upper includes the bolt carrier group, so assembly is straightforward once you have a lower.
The upper group comes complete with bolt carrier group, ZEROED ambidextrous charging handle, ZEROED polymer dust cover, and ZEROED linear compensator for the muzzle.
Short-barrel legality depends on your location and whether you're building a rifle or pistol. Consult your local and federal firearms laws before assembly. Many shooters use short barrels on AR pistols or registered short-barrel rifles (SBRs). This product is a component—final legality is your responsibility.
The muzzle threads at 1/2x28 and the linear compensator included can be swapped for a suppressor of the same thread pitch. Check your suppressor specifications for compatibility with 5.56 rifles.
SKU: 115661997 • Weight: 3oz
Availability: In Stock
Current Stock: Out of stock
The CMMG BANSHEE MK4 5.56x45 10.5" upper group is purpose-built for shooters who prioritize compact size and lightweight handling without sacrificing reliability. At just 10.5 inches, this is CMMG's shortest 5.56mm upper offering—ideal for those building an ultra-compact AR15 that moves fast in tight quarters, fits easily in a vehicle, or simply feels right in your hands. Whether you're assembling a truck gun, a home-defense carbine, or a nimble range build, this upper delivers the firepower of 5.56 in a footprint that goes places bigger rifles can't.
Everything arrives ready to run: the upper comes complete with bolt carrier group, polymer dust cover, ambidextrous charging handle, and CMMG's ZEROED linear compensator. The billet 6061-T6 aluminum upper receiver pairs with an EML9 M-LOK handguard, giving you modern mounting flexibility without excessive weight. The 4140CM barrel features a 1:7 twist and carbine-length gas port, tuned for reliable operation in a short, direct-impingement system with a fixed 0.750" non-adjustable gas block.
At 3.5 pounds and 18.8 inches overall, the BANSHEE MK4 upper prioritizes portability and balance. The muzzle threads at 1/2x28 accept standard suppressors or brakes, and the linear compensator included here helps tame recoil and noise in close-quarters scenarios. The Mk4 platform is a proven CMMG design that keeps the short-barrel concept simple and functional—no exotic systems, just clean engineering that hunters, shooters, and outdoor enthusiasts have relied on.
This is a versatile upper for builders and tinkerers who want precision parts without the guesswork. Pair it with your favorite lower, zero in, and you've got a rifle that handles like a pistol but delivers rifle performance.
| Brand | CMMG |
| Platform | Mk4 AR15 |
| Caliber | 5.56x45mm (.223 Remington) |
| Barrel Length | 10.5" |
| Barrel Twist Rate | 1:7 |
| Barrel Material | 4140CM |
| Barrel Contour | MR |
| Operating System | Direct Impingement |
| Gas Block | 0.750" non-adjustable |
| Gas Port Location | Carbine length |
| Upper Receiver | Billet 6061 T6 aluminum |
| Handguard | CMMG EML9 M-LOK |
| Charging Handle | CMMG ZEROED ambidextrous |
| Muzzle Device | CMMG ZEROED linear compensator |
| Muzzle Thread | 1/2 x 28 |
| Includes | Bolt carrier group, dust cover, charging handle, linear compensator |
| Weight | 3.5 lbs |
| Overall Length | 18.8" |
| Finish | Cerakote (Black) |
The CMMG BANSHEE MK4 upper is built on CMMG's Mk4 AR15 platform and will mate with any standard AR15 lower receiver that accepts a Mk4 upper.
This is an upper group assembly, so you'll need to pair it with an AR15 lower receiver to complete a functional rifle. The upper includes the bolt carrier group, so assembly is straightforward once you have a lower.
The upper group comes complete with bolt carrier group, ZEROED ambidextrous charging handle, ZEROED polymer dust cover, and ZEROED linear compensator for the muzzle.
Short-barrel legality depends on your location and whether you're building a rifle or pistol. Consult your local and federal firearms laws before assembly. Many shooters use short barrels on AR pistols or registered short-barrel rifles (SBRs). This product is a component—final legality is your responsibility.
The muzzle threads at 1/2x28 and the linear compensator included can be swapped for a suppressor of the same thread pitch. Check your suppressor specifications for compatibility with 5.56 rifles.
SKU: 115661997 • Weight: 3oz