The H&K MR556 A4 5.56mm Pistol — 30-Round, Black is a semi-automatic AR-style pistol built for defensive or range use. It chambers .223 REM/5.56 NATO and comes with a single 30-round magazine. The gas piston system reduces fouling inside the action, keeping the gun cleaner longer than a direct-impingement design.
| Manufacturer | Heckler & Koch |
|---|---|
| Model | MR556 A4 Pistol |
| Material | 7075-T6 aluminum upper and lower receivers (per manufacturer specs) |
| Compatibility | .223 REM / 5.56 NATO ammunition; standard AR-15 magazines |
| Finish | Black anodized |
| Weight | Approx. 7.3 lbs (unloaded, per manufacturer specs) |
| Condition | New |
Key Features
- Short-Stroke Gas Piston System — This reduces carbon buildup inside the bolt carrier and chamber, so you can shoot more rounds between cleanings. It also helps the pistol run cooler on hot range days.
- Free-Float M-LOK Handguard — Attach a light, grip, or laser directly to the handguard without affecting barrel harmonics. That means better accuracy when you add gear.
- Fully Ambidextrous Controls — Safety selector, magazine release, and bolt release work from either side. Left-handed shooters or those training with support-hand drills will find it easy to run.
- Threaded Barrel — The 1:7 twist, 10.4-inch barrel is threaded for a muzzle device or suppressor. If you plan to add a can later, this pistol is ready.
- HK-Proprietary Buffer System — The recoil impulse feels smoother than many direct-impingement AR pistols, which helps you get back on target faster for follow-up shots.
Who It’s For
This pistol fits a family who wants a reliable defensive tool that also works for range practice. It’s a good step up from a basic AR-15 for shooters who appreciate HK quality. Beginners will find the ambi controls easy to learn, and experienced shooters will like the reduced maintenance.
Pros & Cons
Pros: Clean-running piston system, ambi controls, M-LOK handguard for accessories, threaded barrel, HK durability.
Cons: Price is higher than many AR pistols — you pay for the HK engineering and the piston system. It also weighs about 7.3 lbs unloaded, which is a bit heavier than some direct-impingement models.
Comparison
| Feature | H&K MR556 A4 Pistol | Geissele Super Duty Pistol | Zev Technologies OZ9C |
|---|---|---|---|
| Operating System | Short-stroke gas piston | Direct impingement | Direct impingement |
| Barrel Length | 10.4 inches | 10.3 inches | 4.5 inches (pistol) |
| Weight (unloaded) | ~7.3 lbs | ~6.5 lbs | ~1.8 lbs |
| Handguard | M-LOK free-float | M-LOK free-float | Proprietary |
| Ambidextrous Controls | Yes (safety, bolt, mag release) | Yes (safety, bolt release) | Yes (safety) |
| Price | $3,749 | ~$1,900 | ~$1,600 |
The Geissele Super Duty is a solid direct-impingement option at a lower price, but it lacks the cleaner-running piston system. The Zev OZ9C is a compact pistol, not a direct AR-pistol competitor, but it shows the price range for premium handguns. For a full-size AR pistol with a piston, the HK is a standout choice.
FAQ
What is the barrel twist rate on the H&K MR556 A4 pistol?
The barrel has a 1:7 twist rate, which stabilizes heavier bullets (62-77 grain) commonly used in 5.56 NATO loads.
Does this pistol come with a muzzle device?
Yes, it ships with a flash hider installed on the threaded barrel. You can replace it with a suppressor or compensator.
Is the H&K MR556 A4 pistol California compliant?
This model ships with a standard 30-round magazine and features that may not meet California’s assault weapon laws. Check your local regulations before ordering.
Can I use standard AR-15 magazines in this pistol?
Yes, it accepts any standard AR-15/M16 magazine. It comes with one 30-round HK magazine.
Ready to Buy
This H&K MR556 A4 5.56mm Pistol — 30-Round, Black is a reliable, low-maintenance AR-style pistol for defensive or range use. Add it to your collection and enjoy the HK piston system.
- ✅ Nationwide delivery (all 50 states)
- ✅ Ships 1-2 business days
- ✅ 30-day returns
- ✅ Secure checkout
Explore more AR Pistols or check our HK Parts & Accessories and AR Uppers.
Last updated: April 2026
FFL Transfer & Firearms Laws for H&K MR556 A4 5.56mm Pistol — 30-Round, Black
All firearms, including the H&K MR556 A4 5.56mm Pistol — 30-Round, Black, 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 H&K MR556 A4 5.56mm Pistol — 30-Round, Black 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 H&K MR556 A4 5.56mm Pistol — 30-Round, Black 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 H&K MR556 A4 5.56mm Pistol — 30-Round, Black?
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 H&K MR556 A4 5.56mm Pistol — 30-Round, Black 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.
What tags or features does this product have?
Key features and tags for this product include: .
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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FFL Transfer & Firearms Laws
All firearms, including the H&K MR556 A4 5.56mm Pistol — 30-Round, Black, must be shipped to a licensed Federal Firearms License (FFL) dealer. A background check and any required local paperwork must be completed before you can take possession.
How It Works
- Place your order online.
- Send us your preferred local FFL dealer info.
- We ship the firearm to your FFL after verification.
- Complete background check and pick up from your dealer.
Legal Compliance
We comply with all U.S. firearm laws. It is your responsibility to ensure the H&K MR556 A4 5.56mm Pistol — 30-Round, Black is legal in your state. Some states (e.g. CA, NY, NJ) have restrictions on magazine size or certain features.
Helpful Links
Need help? Contact our team — we’ll guide you through selecting a compliant firearm and the FFL transfer process.
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