FX-05 Xiuhcoatl

The FX-05 Xiuhcoatl was developed starting in 2005 as a 16-month research project by the Dirección General de Industria Militar del Ejército and CIADTIM. This initiative aimed to replace the HK G3A3 rifles then in service with the Mexican military. Initial plans involved licensed production of the HK G36, but this approach was cancelled in favor of developing a more cost-effective, wholly indigenous rifle. The FX-05 project was undertaken using only national equipment and technology. By December 2006, approximately €5,855,698 had been invested in the project. A legal review with Heckler & Koch regarding potential patent infringement claims related to design similarities with the G36 concluded that despite external appearance, the internal mechanisms were sufficiently different, ending the dispute.

This assault rifle features:

• A receiver constructed primarily from polymer reinforced with carbon-fiber over an underlying titanium frame, available in various colors and camouflage patterns.

• A gas piston system located above the barrel coupled with a multi-lugged rotary bolt.

• A reversible charging handle.

• Semi-automatic fire, three-round bursts, and full automatic fire, with a cyclic rate of approximately 750 rounds per minute.

• Ambidextrous safety/fire mode selectors above the pistol grip.

• A folding and adjustable stock.

• A hammer forged barrel with polygonal rifling.

• An integrated optical sight with a carry handle as a standard feature.

• Compatibility with NATO-standard magazines and specific transparent magazines.

• An internal mechanism and barrel made from corrosion-resistant stainless steel.

• Compatibility with the AG36 grenade launcher; indigenous underbarrel grenade launchers are under development, including a programmable air-burst variant.

The FX-05 is offered in several configurations optimized for different operational roles, including assault rifle, carbine, compact, light machine gun, and sharpshooter variants. These versions are largely identical, with minor differences such as a shortened fore-end on the compact and a fixed adjustable stock on the sharpshooter model. Additional variants have been introduced, including the Xihucóatl Submachine Gun unveiled in 2016 and the PAX-100, with production slated to commence in 2019.

The rifle was officially presented on September 16, 2006, during a military parade, where it was carried by elements of the Special Forces Airmobile Group (GAFE). The FX-05 Xiuhcoatl is currently distributed among the Mexican Armed Forces.