Heckler & Koch HK433

• Name — Heckler & Koch HK433 • Type — Assault rifle Carbine • Design Date — 2017 • Designer — Heckler & Koch • Service — 2024–present • Wars — Russo-Ukrainian war • Action — Gas-operated short-stroke piston, rotating bolt • Origin — Germany • Is Ranged — Yes • Length — (11") (14.5") (16.5") • Weight — (11") (14.5") (16.5") • Cartridge — 5.56×45mm NATO (HK433).300 AAC Blackout (HK437) • Rate — 850 rounds/min • Velocity — (11" barrel) (14.5" barrel) (16.5" barrel) • Feed — 30-round detachable STANAG magazine • Sights — Iron sights and Picatinny rails for various optics

The HK433 was formally introduced at EnforceTac 2017 on 1 and 2 March in Nürnberg, Bavaria, Germany, after having been shown to a select number of people at SHOT Show in January. Heckler & Koch offered the HK433 along with the HK416 as a candidate for the German Bundeswehr's competition (System Sturmgewehr Bundeswehr) to select a new assault rifle. The HK433 has been proposed as a potential successor to the L85 as the next standard service rifle for the British Army under Project GRAYBURN.

• Illustration — Short-stroke gas piston diagram The HK433 was designed by Heckler & Koch to be familiar to operators with experienced with the Heckler & Koch G36 and HK416. All controls are ambidextrous, and major components are modular, allowing for rifles to be configured in the field as needed. The HK433 has multiple barrel lengths including 11, 12.5, 14.5, 16.5, 18.9 and 20 inches. All of the barrels are cold hammer forged, hard chrome lined with a 178 mm (1-in-7 inch) right-hand twist, six-groove rifling. It features a short-stroke gas piston driven system similar to the Heckler & Koch G36 and HK416, with a gas block regulator adjustment located above the barrel. The non-reciprocating charging handle can be changed to operate from either side of the forestock of the rifle, but does not have a locking recess like the Heckler & Koch G3 family of weapons. All other primary controls are ambidextrous. It has an interchangeable barrel system and a folding adjustable buttstock with a three position cheek riser Side-folding the buttstock shortens the HK433 by. The monolithic upper receiver is made of aluminium alloy, and the lower receiver is made of polymer. It is offered with the option of 2 different lower receivers: one with an AR-15 style magazine release button, and one with a paddle magazine release reminiscent of the G36. The HK433 features a STANAG 4694 NATO Accessory Rail at 12 o'clock that is backwards-compatible with the STANAG 2324/MIL-STD-1913 Picatinny rail. At 6 o'clock it features the STANAG 2324/MIL-STD-1913 Picatinny rail. At the 3 and 9 o'clock positions the proprietary "HKey" accessory attachment system, which was used on early versions of the rifle, has been replaced by the more commonly used M-LOK system. The empty weight of a HK433 Draft STANAG 4179 compliant box magazine is approximately.

The Heckler & Koch HK437, chambered in.300 AAC Blackout and featuring 7 and 9 inch barrels, was announced along with the HK433. Currently are three configurations of the HK433 and two configurations of the HK437 available: • Variant — Calibre — Length max. mm — Length min. mm — Barrel mm — Weight g • HK433 11" — 5.56×45mm — 843 — 577 — 280 — 3250 • HK433 14.5" — 5.56×45mm — 931 — 634 — 368 — 3400 • HK433 16.5" — 5.56×45mm — 976 — 718 — 421 — 3500 • HK437 Sneaker 9" —.300 Blackout — 745 — 487 — 178 — 3040 • HK437 Sneaker 11" —.300 Blackout — 795 — 537 — 229 — 3140 While the HK437 was originally announced alongside the HK433 in 2017, there are official sources confirming information about Heckler & Koch expanding the HK433 platform in different caliber variants. • Variant — Calibre — Status • HK433 — 5.56×45mm — Released • HK437 —.300 Blackout • HK231 — 7.62×51mm — In development (2024-01) • HK231 — 6.5 Creedmoor — Announced • HK132E — 7.62×39mm — In development • HK132E — 5.45×39mm — Announced • HK254 — 9×19mm — In development (2024-01)

• Germany: Two contracts were signed for the German Armed Forces: • The Bundeswehr has ordered 988 HK437 rifles for the KSK, designated as the "G39". • A contract of over 200 HK437 along with accessories was procured in October 2022 for a total amount of €1.68 million for the Schleswig-Holstein Police. In 2024, the State police of Schleswig-Holstein announced the intention to replace all of their SIG Sauer MCX and Heckler & Koch MP5 models with up to 1,700 HK437 rifles by 2026. • Ukraine: Main Directorate of Intelligence.