HK21 for Sale
Browse HK21 listings from verified sellers across the U.S. on GunsAmerica.
Quick Look
The HK21, developed by Heckler & Koch in the 1960s, is a versatile general-purpose machine gun based on the G3 rifle. It features a modular design optimized for reliability and adaptability. The HK21 remains popular among military and law enforcement units worldwide for its durability and configurable options.
Why It's a Top Choice
- Robust roller-delayed blowback system
- Easy barrel changes for sustained fire
- Multiple caliber and feed mechanism options
- Compact design for maneuverability
- Strong aftermarket support for parts
Key Variants
HK21A1
Standard version chambered in 7.62x51mm NATO for infantry support roles.
HK21E
Lightweight variant with enhanced ergonomics for special forces.
HK21K
Compact carbine model designed for close-quarters combat.
Competitor Comparison Table
| Feature | HK21 | M249 | FN MAG |
|---|---|---|---|
| MSRP | Varies by variant | Approx. $6,000 | Approx. $7,500 |
| Capacity/Size | Belt-fed, 7.62x51mm | Belt-fed, 5.56x45mm | Belt-fed, 7.62x51mm |
| Weight | Approx. 10.5 lbs | Approx. 17 lbs | Approx. 22 lbs |
| Optics-Ready | Yes, with mounting options | Yes | Yes |
| Trigger Type | Roller-delayed blowback | Gas-operated | Gas-operated |
| Notable Pro | Compact and reliable design | Widely used and trusted | High durability and accuracy |
| Notable Con | Limited availability in civilian market | Heavier than HK21 | Relatively heavy and bulky |
Best Use Cases
- Military squad automatic weapon
- Law enforcement tactical support
- Range training and marksmanship
- Competitive shooting in machine gun categories
- Collection of historic firearms
FAQs
Can I use optics on the HK21?
Yes, the HK21 supports optics mounting with various adapters for scopes and red dots.
What calibers does the HK21 support?
Primarily chambered in 7.62x51mm NATO; some variants accept 5.56x45mm and other NATO rounds.
How does the HK21 differ from the G3 rifle?
The HK21 is a belt-fed machine gun based on the G3’s roller-delayed blowback system but designed for sustained automatic fire and heavier use.
Prefer nearby results? Toggle to search local listings.
HK HKV1 .45 ACP 4.46" Night S MS Black 1
$893.99
HK HKV1 .45 ACP 4.46" Night S MS Black 1
$819.00
Federal FED H121 PROMO 8 25
$13.99
Sign up for our newsletter
Frequently asked questions
What types of firearms does GunsAmerica offer online?
Are there any restrictions to buying legal firearms from GunsAmerica?
What are some of the best firearm companies available at GunsAmerica?
Can I sell my firearm to GunsAmerica?
How does GunsAmerica handle firearm shipping and transfers?
Who We Are
About
From the latest advancements in firearm technology to trusted essentials, GunsAmerica offers a comprehensive selection of gun accessories designed to enhance performance, reliability, and safety. Whether you need precision optics, durable stocks, high-capacity magazines, suppressors, or muzzle devices, our marketplace provides everything required to maintain, upgrade, and customize your firearms. We feature products from leading manufacturers, ensuring superior quality and compatibility across all firearm platforms. Our extensive inventory is built to support every shooter’s needs, from tactical applications and competitive shooting to hunting and everyday carry. At GunsAmerica, we are committed to delivering a seamless, secure shopping experience with competitive pricing, making it easier than ever to find the right accessories to optimize your firearms for any mission or environment.