
Availability: In Stock
Current Stock: Out of stock
The CMMG Banshee MK57 pistol in 5.7x28mm is a modern take on the AR-platform pistol, engineered around one of the fastest-growing defensive cartridges in the country. If you've been curious about 5.7x28mm but didn't want to sacrifice AR-15 ergonomics and controls you already know, the Banshee MK57 bridges that gap. It runs FN Five-seveN pattern magazines, accepts standard AR-15 triggers, and features familiar controls like last-round bolt hold-open—all in a compact, handy package that tips the scales at just 4.8 pounds.
What makes the 5.7x28mm appealing is its low recoil impulse and velocity that punches above its weight class at close range, especially from a shorter barrel. CMMG's MK57 platform was purpose-built for this cartridge, using a radial delayed blowback system tuned for reliable function. The 5-inch 4140CM barrel keeps the overall length to 20.9 inches, making it maneuverable in tight spaces without sacrificing capability. Every component is CMMG's own—from the billet aluminum upper and forged lower receiver to the ZEROED ambi charging handle, pistol grip, and trigger group—so you get a cohesive, well-integrated system rather than a parts-bin special.
The RipBrace gives you a solid cheek weld and support point without the tax and paperwork of a traditional stock, and the CMMG ZEROED linear compensator on the front helps tame what little recoil this round produces. M-LOK mounting on the EML4 handguard lets you add optics, lights, or other accessories as your role demands. Whether you're exploring the 5.7x28mm platform for the first time or you already run a Five-seveN and want rifle-controls compatibility, the Banshee MK57 delivers the goods.
| Caliber | 5.7x28mm |
| Platform | CMMG Banshee MK57 |
| Operating System | Radial Delayed Blowback |
| Barrel Length | 5 inches |
| Barrel Twist | 1:9 |
| Barrel Material | 4140CM steel |
| Barrel Contour | MT |
| Muzzle Device | CMMG ZEROED Linear Compensator |
| Muzzle Thread | 1/2 x 28 |
| Upper Receiver | Billet 6061-T6 Aluminum |
| Lower Receiver | Forged 7075-T6 Aluminum (Mk57) |
| Handguard | CMMG EML4 M-LOK |
| Charging Handle | CMMG ZEROED Ambi |
| Trigger | CMMG ZEROED Drop-In Single Stage |
| Trigger Guard | Integrated |
| Safety Selector | CMMG ZEROED 60/90 Degree |
| Pistol Grip | CMMG ZEROED |
| Stock/Brace | CMMG RipBrace |
| Buffer Type | Carbine |
| Receiver Extension | CMMG 6-Position Fastback |
| Magazine | 20-round Promag |
| Finish | Cerakote Standard |
| Weight | 4.8 lbs |
| Length | 20.9 inches |
The Banshee MK57 is designed to use FN Five-seveN pattern magazines. It ships with a 20-round Promag.
Yes. The Banshee MK57 is built on an AR-compatible platform and accepts standard AR-15 triggers. It also features familiar AR controls including a last-round bolt hold-open function and a standard safety selector interface.
The Banshee MK57 has a 5-inch barrel and an overall length of 20.9 inches, making it compact and maneuverable while still delivering the capability of the 5.7x28mm cartridge.
The pistol ships with a CMMG RipBrace, one 20-round Promag magazine, CMMG ZEROED charging handle, trigger, safety, and pistol grip, plus the CMMG ZEROED linear compensator already installed on the muzzle.

SKU: 126818325 • Weight: 6.32oz




Availability: In Stock
Current Stock: Out of stock
The CMMG Banshee MK57 pistol in 5.7x28mm is a modern take on the AR-platform pistol, engineered around one of the fastest-growing defensive cartridges in the country. If you've been curious about 5.7x28mm but didn't want to sacrifice AR-15 ergonomics and controls you already know, the Banshee MK57 bridges that gap. It runs FN Five-seveN pattern magazines, accepts standard AR-15 triggers, and features familiar controls like last-round bolt hold-open—all in a compact, handy package that tips the scales at just 4.8 pounds.
What makes the 5.7x28mm appealing is its low recoil impulse and velocity that punches above its weight class at close range, especially from a shorter barrel. CMMG's MK57 platform was purpose-built for this cartridge, using a radial delayed blowback system tuned for reliable function. The 5-inch 4140CM barrel keeps the overall length to 20.9 inches, making it maneuverable in tight spaces without sacrificing capability. Every component is CMMG's own—from the billet aluminum upper and forged lower receiver to the ZEROED ambi charging handle, pistol grip, and trigger group—so you get a cohesive, well-integrated system rather than a parts-bin special.
The RipBrace gives you a solid cheek weld and support point without the tax and paperwork of a traditional stock, and the CMMG ZEROED linear compensator on the front helps tame what little recoil this round produces. M-LOK mounting on the EML4 handguard lets you add optics, lights, or other accessories as your role demands. Whether you're exploring the 5.7x28mm platform for the first time or you already run a Five-seveN and want rifle-controls compatibility, the Banshee MK57 delivers the goods.
| Caliber | 5.7x28mm |
| Platform | CMMG Banshee MK57 |
| Operating System | Radial Delayed Blowback |
| Barrel Length | 5 inches |
| Barrel Twist | 1:9 |
| Barrel Material | 4140CM steel |
| Barrel Contour | MT |
| Muzzle Device | CMMG ZEROED Linear Compensator |
| Muzzle Thread | 1/2 x 28 |
| Upper Receiver | Billet 6061-T6 Aluminum |
| Lower Receiver | Forged 7075-T6 Aluminum (Mk57) |
| Handguard | CMMG EML4 M-LOK |
| Charging Handle | CMMG ZEROED Ambi |
| Trigger | CMMG ZEROED Drop-In Single Stage |
| Trigger Guard | Integrated |
| Safety Selector | CMMG ZEROED 60/90 Degree |
| Pistol Grip | CMMG ZEROED |
| Stock/Brace | CMMG RipBrace |
| Buffer Type | Carbine |
| Receiver Extension | CMMG 6-Position Fastback |
| Magazine | 20-round Promag |
| Finish | Cerakote Standard |
| Weight | 4.8 lbs |
| Length | 20.9 inches |
The Banshee MK57 is designed to use FN Five-seveN pattern magazines. It ships with a 20-round Promag.
Yes. The Banshee MK57 is built on an AR-compatible platform and accepts standard AR-15 triggers. It also features familiar AR controls including a last-round bolt hold-open function and a standard safety selector interface.
The Banshee MK57 has a 5-inch barrel and an overall length of 20.9 inches, making it compact and maneuverable while still delivering the capability of the 5.7x28mm cartridge.
The pistol ships with a CMMG RipBrace, one 20-round Promag magazine, CMMG ZEROED charging handle, trigger, safety, and pistol grip, plus the CMMG ZEROED linear compensator already installed on the muzzle.
SKU: 126818325 • Weight: 6.32oz
