Khaosmatic

You looking for that specific one? I have a nice one I could part out to you from dervgu 
it’s a full m16 metal receiver!
also have a ris plate and 4x scope that’s specific to the m16 receiver 

Best bet is to buy a new one from China or Taiwan bud. THey're quite a specialist thing so if somebody has one they aren't going to be selling it. airsoftglobal still have a load of trademarked receivers if you start there
http://www.airsoftglobal.com/shop/index.php?main_page=product_info&cPath=32_222&products_id=2322