2013-11-28 / 17:57 UTC GMT +00:00
Technically it is the serial number that matters, if the real steel equivalent has a serial number on that part it should not be imported. That being said the only item that seems to be spotted for this is lower frames. Generally outer barrels, slides, etc.. are fine even though the real steel versions have serial numbers on them in many cases.
VFC Noveske M4 - Echo1 Platinum M16 - G&G Top Tech RK47 - Ares Stoner LMG
TM MK23 Socom - KJW Glock 23 - KJW P226