HK21 machine gun

E197571

The HK21 machine gun is a German-designed, belt-fed general-purpose machine gun developed by Heckler & Koch and based on the G3 rifle’s roller-delayed blowback system.

Try in SPARQL Jump to: Surface forms Statements Referenced by

All labels observed (3)

Statements (49)

Predicate Object
instanceOf belt-fed machine gun
firearm
general-purpose machine gun
action roller-delayed blowback
barrelFeature quick-change barrel
basedOn Heckler & Koch G3 rifle
caliber 7.62 mm
canBeConvertedTo magazine feed using G3 magazines
cartridge .308 Winchester (commercial equivalent)
7.62×51mm NATO
category crew-served weapon
chamberType fluted chamber
countryOfOrigin Germany
designer Heckler & Koch
feedSystem belt-fed
magazine-fed (with conversion)
fireModes fully automatic
selective fire
gasSystem no gas system (recoil-operated, roller-delayed)
hasVariant HK11
HK13
HK21
surface form: HK21A1

HK21
surface form: HK21E

HK23
HK23E
intendedUse infantry support weapon
introducedInDecade 1960s
isPartOf HK21 machine gun self-linksurface differs
surface form: Heckler & Koch 20-series machine guns
manufacturer Heckler & Koch
mountingOptions bipod
tripod
vehicle mount
operatingPrinciple roller-delayed blowback with fluted chamber
primaryRole general-purpose machine gun
rateOfFire approximately 800 rounds per minute
relatedWeapon Heckler & Koch G3 rifle
surface form: Heckler & Koch G3

Heckler & Koch MG5
safety selector lever with safe and fire positions
sightType iron sights
optical sight (with mounts)
stockType fixed stock (standard)
optional retractable stock
usedBy Brazilian Armed Forces
surface form: Brazilian armed forces

German armed forces (limited and special units)
Armed Forces of Greece
surface form: Greek armed forces

Portuguese Armed Forces
surface form: Portuguese armed forces

various police and special forces units worldwide
usedInConflict Cold War-era conflicts
Vietnam War (by some users)

How these facts were elicited

The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.

Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10.

# Requirements
- If you don't know the subject at all, return an empty list.
- If the subject is not a named entity, return an empty list.
- Include at least one triple where predicate is "instanceOf".
- Do not get too wordy.
- Separate several objects into multiple triples with one object.
Input
Subject: HK21 machine gun
Description of subject: The HK21 machine gun is a German-designed, belt-fed general-purpose machine gun developed by Heckler & Koch and based on the G3 rifle’s roller-delayed blowback system.

Referenced by (3)

Full triples — surface form annotated when it differs from this entity's canonical label.

Heckler & Koch product HK21 machine gun
Bren light machine gun successor HK21 machine gun
this entity surface form: L7A2 GPMG
HK21 machine gun isPartOf HK21 machine gun self-linksurface differs
subject surface form: HK21
this entity surface form: Heckler & Koch 20-series machine guns