 The report concluded that while externally the FX-05 bears obvious design elements there are several notable differences.The receiver which was styled after the G36 is in fact coupled with a simple gas piston similar in operation to the AK series which is then attached through a delayed roller system to the weapons recoil delaying system.While the more advanced parts of the rifle were found to be independently Mexican produced, Heckler & Koch officials still questioned the DGIM (the manufacturer of the FX-05) regarding the issue of the rifles receiver system which is almost identical to the G36's.