Banner

HK21

GunCritic Score

Critic Rating

User Rating

0 Reviews

MSRP:

$5400.00

Used Price:

$5,400.00

Sale Price:

$6000.00

HK21 Gun Stats

Want to Sell Your Gun?

Get Instant Offer
The HK21 is, in the simplest terms, a belt-fed G3. Designed by Heckler & Koch in 1961, the German Bundeswehr actually failed to adopt the new design since they had just recently adopted the MG3 and were happy with its performance. The HK21 would then be given an "E" designation demarking its export status. The most notable user of the HK21 was Portugal who adopted a significant number of these guns. HK is still producing the HK21 in an export capacity as of 2023.

HK21 Specs

1 Brand

HK

2 Category

Technical Data

Capacity

100 Round Belt

Weight

280 oz

Barrel Length

17.7"

Length

40.2"

HK21 Features

The Heckler & Koch HK21 is a select-fire, roller-delayed blowback operated select-fire rifle that can be fired in semi- and full-auto and even in 3-round bursts if your battalion commander orders that.  The rifle is built with a quick-change barrel system that allows the user to replace hot barrels with a cold one in a matter of seconds.  The rear sight on the HK21 is switched out for a range-adjustable rear aperture instead of the diopter sight.


HK21 Capacity

The HK21 is chambered in 7.62x51mmNATO and, thanks to its modular design, is able to be set up with a magazine well allowing it to accept the G3 pattern 20 round box magazines or configured to accept belts of ammo.  These can consist of 50, 75 and 100 round belts on non-disintegrating links or M13-linked belts that have no limit outside of the container they’re held in.


Measuring 40.2 inches long with an unloaded weight of 17.5 pounds, the HK21 offers one of the best firepower-to-weight platforms.  Even though it weighs twice as much as a G3 due to its heavy-profile barrel, longer receiver and extra feed mechanisms, it still weighs less than more common 7.62x51 caliber belt-fed guns like the M240 and the MG3.  


HK21 Mobility

Mobility

HK21 Ergonomics

Ergonomics
The HK21 has the same control setup as the G3 with the only major difference being the way belts are loaded.  The charging handle’s length of travel is noticeably longer as the gun’s receiver was lengthened to accommodate the new ammo feeding system as well as to reduce felt recoil.  The handguard is open on the right side to allow for rapid barrel swapping, so a 45 degree front grip is often found on the HK21.


HK21 Fit & Finish

The HK21 is built to the same standards as the G3, MP5 and other HK rifles of this pattern, and has extra reinforcements added to the receiver to improve its durability.  Even though it’s a light machine gun, the HK21 fires from the closed bolt and while this allows it to be just as accurate in semi-auto as the G3, it does put the user at risk of cook-offs if the barrel gets too hot.


Fit and Finish

How much is a HK21 worth?

In 2025 a new or used HK21 value varies depending on supply and demand. In the last 12 months there is great demand for a HK21 and most other rifles. The Price for a HK21 has increased in cost by $0.00 in 2025 compared to 2024.

Estimated New and Used Values for a HK21 Values are based on a basic model with no options or colors.

Condition Trade-In Private Party Dealer
New In box $3,900.00 $5,100.00 $6,000.00
Excellent $3,600.00 $4,800.00 $5,400.00
Very Good $3,300.00 $4,800.00 $5,400.00
Good $3,000.00 $4,500.00 $5,100.00
Fair $2,100.00 $3,900.00 $4,800.00
Poor $1,500.00 $3,000.00 N/A

Gun Value Conditions explained:

New in box - 100% condition in unopened box. Excellent - 95%+ condition with or without box.

Very Good - 90% - 95% condition (all parts/finish should be original).

Good - 80-90% condition (all parts/finish should be original).

Fair - 30% - 80% condition, parts, and finish may or may not be original. Must function properly and shoot.

Poor - under 30% condition. Firearm has severe wear and tear, does not function, or is damaged.

Guncritic Icon

Want To Sell Your HK21?

Quick Cash Offer

  • We make you an quick cash offer online

  • We find the dealer that offers you the most money

  • Get cash for your gun or do a trade in

How We Compare to Selling It Yourself

We take all the hassle out of selling your gun.

Speed Icon

Save Time

Quick Cash Offer

Get your cash offer in minutes

Selling it Yourself

Can take months to sell your gun privately

Buyer Icon

Buyer

Quick Cash Offer

Trusted retailers will pay you for your gun

Selling it Yourself

You don't know who you're selling to, or if they'll rip you off

Price Icon

Price

Quick Cash Offer

I'ts totally free to get a cash offer on your gun

Selling it Yourself

It costs money to place ads to sell your gun, and it takes a lot of time

Diffuculty Icon

Difficulty

Quick Cash Offer

Easy online paperwork and registration process for your safe and legal payout

Selling it Yourself

You have to trust the buyer to pay you, and trust that you're following the law

Rate And Review

HK21 Q & A

There are no questions related to HK21

/

HK21 Problems

There are no problems related to HK21

/

Related Products