CRC 9HK140 - Improved Magwell for HK G36

Heckler & Koch Gewehr 36 is a standard-issue rifle of the German Army that found its way to Ukraine as part of military aid deliveries. When an entire army is equipped with a unified weapons platform—differing only in barrel length and stock configuration—logistical issues are generally minimal. However, once the G36 entered the "wild field," that is the eclectic small arms inventory of the Ukrainian Defense Forces, its partially proprietary nature became increasingly apparent. This is especially true regarding the magazine — arguably the firearm component the shooter interacts with most frequently.

The G36 magazines are notable for being made of transparent polymer, which allows for visual round count monitoring, and for their molded coupling lugs. These features enable standard-issue dual-magazine setups, or even triple configurations (and we know for a fact that soldiers issued the G36 have at least once attempted to link together as many mags as they had on hand) for faster reloads under pressure.

These magazines are inserted in a manner somewhat similar to AK-pattern mags — hooked into the magwell via a rear lug. While the motion is nearly identical, where's the problem if the magazines are so well-designed?

The issue lies in logistics: only two magazines were typically issued per rifle. They are significantly more expensive than most alternatives and are only compatible with the G36. This makes losing one far more painful—especially during emergency reloads—compared to using far more common STANAG 4179-compatible magazines, which fit the majority of AR-platform firearms.

The German Army's G36 rifle, transferred to Ukrainian forces, is shown here equipped with an upgraded magazine well 9HK140 by KRUK.

This question was originally brought to KRUK by servicemen, and it was from this request that the CRC 9HK140 magazine well was born — an enhanced version of the standard G36 magwell, designed to accept AR/M-platform magazines.

While Heckler & Koch offers a similar adapter, it comes with a major drawback: a single magazine release button. This significantly reduces both the speed and convenience of reloads, making it unsatisfactory for operational needs.

One of the key advantages of KRUK’s design is its reversibility: the magwell can be installed and removed without any invasive modifications to the rifle. The original part can be safely retained and reinstalled if needed.

Installed improved magwell, with all 3 levers visible

The structural strength of the CRC 9HK140 is on par with the reinforced polymer receiver of the G36 itself. This applies both to the body of the adapter and its magazine release levers — two out of three are ambidextrous. The forward release lever, positioned in front of the trigger guard and operated by the index finger—just like on the original G36—is equal in both quality and ease of use when dropping the magazine.

Ways to detach the magazine from the new improved magwell

Important – to ensure proper bolt catch operation, make sure the magazines you are using have less material on the rear side. If necessary, remove the excess material (as shown in the photo).

Left to right: Magpul PMAG GEN 2 – excess polymer needs to be removed (using a sharp knife or a Dremel tool) to match the appearance of the magazine on the right – the factory look of the Magpul PMAG GEN 3.