[1] In 2012, the G36 was found to suffer from significant accuracy issues due to thermal expansion of the barrel, prompting a search for a replacement.

This weapon was intended to replace the G3, therefore further development of Heckler & Koch's series of firearms chambered for the 5.56×45mm NATO cartridge had been halted.

Heckler & Koch, having no incentive to pursue a new 5.56 mm weapon system, was content with the export-oriented HK33 and G41 rifles.

However, the G11 program came to an abrupt end when the Bundeswehr cancelled its procurement due to defence budget cuts resulting from the unification of East and West Germany, and Heckler & Koch's 1991 acquisition by British Aerospace's Royal Ordnance division (known today as BAE Systems).

[7] In April 2012, reports surfaced that G36 rifles used in Afghanistan would overheat during prolonged firefights after several hundred rounds were fired.

[9][10][11] In February 2014, the German Federal Ministry of Defence announced that the overheating deficiencies of the G36 were not a result of weapon design, but of the ammunition.

A report by the Bundeswehr on 21 February 2014 revealed that the issues were not the fault of the rifle, but that one manufacturer of ammunition was making bullets with copper-plated jackets that were too thin.

[12][13][better source needed] The manufacturer of the ammunition confirmed this,[14] although experts disagreed, and also said the accuracy problems were already known to the defence ministry by 2010.

[16] On 30 March 2015, Minister of Defence Ursula von der Leyen told Associated Press that the weight-saving design was the root of the issues.

[17] This was based on a letter from Inspector General Volker Wieker advising the Stewards of Defence and Budget Committee of the Bundestag and the troops in advance of publication of the report.

[24] In 2016, the Ministry of Defence attempted to sue Heckler & Koch, saying they were legally obligated to repair the subpar G36 rifles.

Because the Bundeswehr did not make its specifications for the weapon clear enough in the beginning of the procurement process,[25][3] the District Court of Koblenz rejected claims from the Bundeswehr procurement office, and ruled that Heckler & Koch did not have to pay damages on the 167,000 rifles still in use out of more than 176,000 G36 rifles Germany had originally purchased.

However, German authorities cancelled the contract the next month amid allegations that the MK 556 infringed on Heckler and Koch patents, and the G95A1 (known as the HK416 A8 during field testing) was selected in early 2021.

Haenel sued to attempt to reverse the decision, but a German court dismissed the lawsuit in June 2022.

While modifications can vary, all G36 variants share an identical receiver, buttstock assembly, bolt carrier group, return mechanism, and guide rod.

The receiver contains the barrel, carry handle with integrated sights, trigger group with pistol grip, handguard and magazine socket.

[citation needed] The fire and safety selector is ambidextrous and has controls on both sides of the receiver; this feature is inherited from the design of the original G3.

[citation needed] Certain types of Beta C-Mags, which hold 100 rounds, can also be used with the stock G36, and are employed by the MG36 variant.

The ejection port has a brass deflector that helps left-handed users avoid being struck by casings.

The rifle can be fitted with a 40 mm AG36 (AG—Anbau-Granatwerfer) under-barrel grenade launcher, which loads via a side-tilting break action.

Standard equipment supplied with the G36 includes: spare magazines, a cleaning and maintenance kit, sling, speedloader and sometimes modified AKM type II blade bayonets (many of which are left over in Germany from stocks of the former National People's Army).

The G36A2 includes the shorter G36C stock, a new handguard made of aluminium (permitting better heat dissipation during sustained fire), an optional four Picatinny rails, and a vertical foregrip with an integrated switch for the LLM01 laser light module.

It adds the proprietary HKey mod system to the handguard, a heavier barrel, and a carry handle with a MIL-STD-1913 Picatinny rail.

The MG36 (MG—Maschinengewehr "machine gun") is an automatic rifle variant of the G36 equipped with a heavier barrel for increased thermal performance and cook-off resistance.

Heckler & Koch also created the semi-automatic SL8 rifle and the straight-pull, bolt-action R8, which are offered to the civilian sport shooting markets, both are loosely based on the G36.

The SL8 is substantially different from the G36, it has a modified receiver and a thumbhole stock with a cheek rest, which is integral with the trigger group.

The rifle uses a 10-round single-stack magazine and an extended top rail used to mount a wide variety of Picatinny-standard optics.

Mounted to the rail are a set of iron sights with a hooded foresight and adjustable flip rear aperture.

In November 2013, Heckler & Koch applied for permission from the German Government to sell a new civilian-legal version of the G36.

According to Steyr, the components of this upgrade kit (metal receiver, barrel and magazine well) can be mounted independently on existing G36 arms without any modifications.