# HK MR556 A4 5.56x45mm 16.5in Black

**Brand:** Heckler & Koch
**Category:** AR Style Rifles
**Caliber:** 5.56 NATO

## Specifications

- **Caliber:** 5.56 NATO
- **Barrel Length:** 16.5"
- **UPC:** 642230269408
- **SKU:** UCBJ1QlAO

## Description

The HK MR556 A4 is a semi-automatic AR-pattern rifle chambered in 5.56x45mm with a 16.5-inch barrel. It has a black finish, an M-LOK handguard, and a 30-round magazine. The rifle accepts both 223 Remington and 5.56x45mm ammunition.

### Key Specifications
- **Brand**: HK
- **Model**: MR556 A4
- **Caliber**: 5.56x45mm
- **Action**: Semi Auto
- **Capacity**: 30
- **Barrel Length**: 16.5 in
- **Color/Finish**: Black

### Detailed Features
- 16.5-inch barrel in black finish
- M-LOK handguard
- 30-round magazine included
- Chambered for 223 Remington and 5.56x45mm

## Frequently Asked Questions

**Q: What caliber is the HK MR556 A4?**

A: The MR556 A4 is chambered in 5.56x45mm and also accepts 223 Remington ammunition.

**Q: Who makes the MR556 A4?**

A: The MR556 A4 is made by HK (Heckler & Koch).

**Q: What type of firearm is the HK MR556 A4?**

A: It is a semi-automatic AR-pattern rifle with an M-LOK handguard.

**Q: What is the barrel length of the HK MR556 A4?**

A: The MR556 A4 has a 16.5-inch barrel.

**Q: How many rounds does the HK MR556 A4 hold?**

A: It comes with a 30-round magazine.

**Q: Where can I buy the HK MR556 A4?**

A: Compare current vendor offers on this page.

## What Customers Say

*AI-generated insights from customer reviews*

Owners of the HK MR556 A4 consistently point to German build quality and tight tolerances as the main reason they chose it over other AR-pattern rifles. The M-LOK handguard is well regarded for its slim profile and practical rail real estate. Most owners run it as a precision or competition semi-auto and find the 16.5-inch barrel a good balance for that use.

The 30-round capacity is standard and draws little comment on its own, but the overall reliability record of the MR556 comes up frequently as a positive. The trigger is described as adequate but not exceptional, and many owners upgrade it after a break-in period.

Value is the recurring debate. The MR556 A4 commands a significant premium over domestic AR-pattern rifles in the same configuration, and owners are split on whether HK's build standards justify the difference. Those who have run it hard tend to think it does; those who shoot casually sometimes feel the cost is hard to rationalize.

## Pricing

**9 offers available**

| Vendor | Price |
|--------|-------|
| Palmettostatearmory Com | $3449.00 |
| Bereli | $3449.00 |
| Gunbuyer Com | $3749.00 |
| Kygunco Com | $3749.00 |
| Classicfirearms Com | $3749.00 |
| Grabagun Com | $3749.00 |
| Primaryarms Com | $3749.00 |
| Gritrsports Com | $3749.00 |
| Buds Gun Shop | $3749.99 |

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*Data from [GunsNation](https://gunsnation.com)*