Armalite AR-10 vs Heckler & Koch HK91

1956–present

1977–2000

Tens of thousands (original), widespread modern clones

~250,000 estimated

1016 mm

1,020 mm (40.2 in) with stock extended

508 mm

508 mm (20.0 in)

4.0–4.5 kg

4.3 kg (9.5 lb) empty

20 rounds

20 rounds standard, 10‑round low‑profile magazines available for restricted markets

direct impingement or piston

Roller‑delayed blowback, closed bolt

single-stage

Single‑stage semi‑automatic trigger with manual safety lever

Iron sights or optics

Adjustable rotary drum rear sight (100‑800 m) and hooded front post; optional telescopic sight mounting rail on receiver cover