JG hk416 upper reciever compatibility
I'm fairly new to the sport and recently purchased a jg hk416 . the one with plastic reciever and battery in stock . I wanted to know if id be able to attach the upper reciever of my hk416 to the metal m4 lower recievers out there? also will there be any issues with the jg plastic upper reciever on a metal m4 lower reciever ?