The CMMG Banshee MK57 5.7x28mm 20+1 Pistol is a compact semi-automatic pistol built on the Mk57 platform, designed to accept FN Five-seveN pattern magazines for reliable feeding. It ships with a full kit of CMMG ZEROED components, including a radial delayed blowback operating system that reduces recoil and muzzle rise. The package includes an M-LOK handguard, Picatinny rail atop the receiver, a threaded medium-taper nitride barrel, and a 20-round ProMag magazine — all ready to hit the range or serve as a home defense tool.
| Manufacturer | CMMG, Inc. |
|---|---|
| Model | Banshee MK57 |
| Material | 7075-T6 aluminum upper and lower receiver, steel barrel (per manufacturer specs) |
| Compatibility | FN Five-seveN pattern magazines |
| Finish | Black anodized receiver, nitride barrel |
| Weight | 5 lbs 12 oz (unloaded, per manufacturer specs) |
| Condition | New |
Key Features
- Radial Delayed Blowback System — Why it matters: This patented system reduces felt recoil by up to 30% compared to direct blowback designs, keeping the muzzle flat for faster follow-up shots, especially important for new shooters.
- CMMG ZEROED Trigger Group — Why it matters: The trigger breaks cleanly at 4.5 lbs with a short reset, giving you consistent control shot after shot, so your family can build good habits from day one.
- Threaded Medium-Taper Nitride Barrel — Why it matters: The 5.7x28mm barrel is threaded 1/2×28 and nitride-coated for corrosion resistance, letting you add a suppressor or compensator for quieter range sessions or reduced muzzle rise.
- Oversized Magazine Release — Why it matters: The extended release makes reloads intuitive even with gloved hands, reducing fumbling during training or in a self-defense scenario.
- M-LOK Handguard with Full-Length Picatinny Rail — Why it matters: The 7-inch M-LOK handguard gives you plenty of real estate for lights, lasers, or grips, while the top Picatinny rail accepts optics like red dots or magnifiers.
Who It’s For
This pistol is built for families who want a lightweight, low-recoil platform for training, home defense, or plinking. The 5.7x28mm caliber offers flat trajectory and moderate stopping power, making it a great choice for newer shooters or those who prefer a smaller-framed AR-style pistol without the weight of a full-size rifle.
Pros & Cons
- Pros: Very low recoil, accepts common FN Five-seveN mags, threaded barrel for suppressors, comes with CMMG ZEROED trigger group
- Cons: Ammo cost is higher than 9mm, and the 5.7x28mm round has less stopping power than .223/5.56 for self-defense beyond 100 yards
Comparison vs. Competitors
| Feature | CMMG Banshee MK57 | Zev Technologies OZ9C | Lone Wolf Distributors Dusk 19 |
|---|---|---|---|
| Caliber | 5.7x28mm | 9mm | 9mm |
| Operating System | Radial delayed blowback | Striker-fired | Striker-fired |
| Magazine Capacity | 20+1 | 15+1 | 15+1 |
| Barrel Length | 8 inches (threaded) | 4.5 inches | 4.6 inches |
| Weight (unloaded) | 5 lbs 12 oz | 1 lb 13 oz | 1 lb 12 oz |
| MSRP | $1,504.26 | $1,799.99 | $1,199.99 |
FAQ
Is the CMMG Banshee MK57 reliable with different ammo brands?
Yes, it cycles reliably with most major brands like Federal, Remington, and Winchester 5.7x28mm ammunition. The radial delayed blowback system handles a wide range of bullet weights from 27 to 40 grains without issues.
Can I mount a red dot sight on this pistol?
Absolutely. The upper receiver has a full-length Picatinny rail, so you can mount any standard red dot, holographic sight, or magnifier. Just use the correct mount for your optic.
Does this pistol come with a case or any accessories?
Yes, it ships in a hard plastic case with the CMMG ZEROED trigger group, one 20-round ProMag magazine, a cleaning rod, and a cable lock. No optics or extra mags are included.
What is the warranty on this pistol?
CMMG backs the Banshee MK57 with a limited lifetime warranty for the original owner. It covers defects in materials and workmanship but not wear items like springs or barrels.
How does the radial delayed blowback system affect cleaning?
It reduces gas blowback into the action, so the bolt and chamber stay cleaner than direct blowback designs. You’ll still want to clean it every 500-800 rounds, but it’s easier to maintain overall.
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Last updated: April 2026
FFL Transfer & Firearms Laws for CMMG Banshee MK57 5.7x28mm 20+1 Pistol
All firearms, including the CMMG Banshee MK57 5.7x28mm 20+1 Pistol, must be shipped to a licensed Federal Firearms License (FFL) dealer. You will be required to complete a background check and any necessary paperwork before taking possession.
How It Works
- Place your order online.
- Provide your preferred FFL dealer information.
- We ship the firearm directly to your FFL.
- You complete the background check and pickup at the FFL.
Legal Compliance
We comply with all federal and state firearm laws. It is your responsibility to ensure the CMMG Banshee MK57 5.7x28mm 20+1 Pistol is legal in your state. Some states may have restrictions on certain firearm models or features.
Helpful Resources
Need assistance? Contact our Miami store for help with FFL transfers and firearm compliance.
Frequently Asked Questions About This Product
Why buy CMMG Banshee MK57 5.7x28mm 20+1 Pistol from Miami Shooters Supply?
We’re a trusted firearms dealer offering fast shipping, competitive pricing, and 100% compliance with U.S. federal firearm laws. All orders ship from our licensed facility with full tracking and expert customer service.
Where can I buy CMMG Banshee MK57 5.7x28mm 20+1 Pistol?
You can purchase this item directly on our website and have it shipped to your local FFL dealer. You can also visit us in-store in Miami, Florida.
Is CMMG Banshee MK57 5.7x28mm 20+1 Pistol available now?
Availability is shown live on this page. If the “Add to Cart” button is visible, this item is currently in stock and ready to ship.
What category does this product belong to?
This product is listed under: AR Pistols.
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Is this product legal in my state?
It is your responsibility to ensure this item is legal in your state or locality. We ship only to valid FFL dealers in compliance with U.S. laws. Always check your local regulations.




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