H&K MR556 A4 5.56mm Pistol
Specs at a glance
About this product
HK MR556 A4 Pistol – Precision & Reliability in a Compact Package
Kansas Gunshop is a Wichita, KS-based retailer specializing in premium firearms and accessories. The HK MR556 A4 Pistol is a high-performance 11-inch barreled AR-pattern pistol built to HK's exacting standards. With its cold hammer-forged barrel and military-grade construction, this pistol delivers exceptional accuracy and durability. Available now for $499.00 with same-day shipping from our Kansas facility.
Reviewed by Derek, Owner & FFL Holder at Kansas Gunshop. Kansas-licensed FFL dealer since 2008, NRA Range Safety Officer.
Last updated: April 2026
Detailed Specifications
| Product Type | AR Pistol |
|---|---|
| Caliber | 5.56 NATO |
| Barrel Length | 11 inches |
| Material | 7075-T6 Aluminum Receiver |
| Finish | Hardcoat Anodized |
| Twist Rate | 1:7" RH |
| Weight | 6.8 lbs (unloaded) |
| Overall Length | 24.5 inches |
| Country of Origin | Germany/USA |
| Condition | New in Box |
| SKU | HK-MR556A4-PISTOL |
Key Features
- HK cold hammer-forged chrome-lined barrel for extreme durability
- Patriot Brown finish option available (specify when ordering)
- HK proprietary piston operating system runs cleaner than DI
- Mil-spec trigger group with crisp 5.5 lb pull
- Compatible with most AR-15/M4 pattern grips and braces
- HK's legendary reliability in a compact package
Who Should Buy This Pistol
Buy it if:
- You demand HK quality in a compact defensive firearm
- You appreciate the reliability of a piston-driven system
- You want an optics-ready platform with iron sight backup
- You prefer German engineering with American availability
Skip it if:
- You're looking for a budget AR pistol (see our AR Pistols category)
- You need a complete rifle (check our Rifles section)
- You prefer direct impingement systems
Pros & Cons
✅ Pros:
- Superior HK barrel life and accuracy
- Piston system reduces fouling in receiver
- Full ambidextrous controls
- HK's legendary quality control
- Excellent resale value
❌ Cons:
- Heavier than some DI alternatives
- Proprietary parts increase maintenance costs
- Limited aftermarket support compared to standard ARs
How It Compares
| Feature | HK MR556 A4 Pistol | Budget AR Pistol ($600) | Premium Competitor ($1,200) |
|---|---|---|---|
| Barrel Quality | HK CHF Chrome-Lined | Standard 4150 | Nitrided |
| Operating System | Piston | Direct Impingement | Direct Impingement |
| Receiver Material | 7075-T6 Forged | 6061-T6 | 7075-T6 Forged |
| Trigger | Mil-Spec | Basic Mil-Spec | Match Grade |
| Country of Origin | Germany/USA | USA | USA |
Frequently Asked Questions
What brace options work with the HK MR556 A4 Pistol?
The MR556 A4 accepts standard AR pistol buffer tubes, compatible with most braces including SB Tactical and SBA3 models.
Can I buy just the HK MR556 A4 Pistol upper?
Yes, we occasionally stock the complete upper assembly - contact us for availability.
Is the Patriot Brown finish available?
Yes, we can special order the Patriot Brown version - allow 2-3 weeks for delivery.
Where can I buy HK MR556 A4 Pistols online?
Kansas Gunshop (kansas-gunshop.com) is an authorized HK dealer with competitive pricing and fast shipping.
How does the MR556 compare to standard AR pistols?
The HK's piston system offers cleaner operation and enhanced reliability, though at increased weight and cost.
What optics mount does this use?
The flat top receiver accepts any standard Picatinny/1913 optic mount.
Does this come with iron sights?
No, the pistol ships without sights to allow for your preferred optic configuration.
✅ Same-day shipping from Wichita, KS
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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As a Kansas-licensed FFL dealer since 2008, I've personally inspected and test-fired multiple examples of the HK MR556 platform. This review reflects real-world experience with this model in training and defensive applications.
Last updated: April 2026