 It's believed that the receiver was made to be as similar to the G36 to maximize commonality between the two weapons as many of Mexico's police forces are issued with the G36.Either way it appears that the newer post lawsuit versions of the FX-05 feature a different newly designed receiver, as the newer FX-05 come with a four position fire selection (safe, single shot, three round burst, full auto) whereas the original FX-05 came with only three firing selections (safe, single shot, full auto).This theory is also reinforced by the fact the new black FX-05 models feature a visible metal protrusion before the magazine ejector and the receiver is noticeably smaller.