The best fake cans I have ever seen were the Advanced Armament Corp (AAC) produced M4 2000 (black) and SCAR (tan) that came with an authentic Blackout flash hider that interfaced with the can....as does the real one. These were offered here by a memeber (can`t recall his name) on CGN a few years ago. I bought one from Target Sports and a few from EE. They were in the $300 range and are very rare now....wish I would not have sold the ones I had just because they are now collectible items. As one knows, AAC produces some of the finest real suppressors on the market today. The fake cans they made could be "shot" with in place on the firearm. We had a few out to the range and they functioned flawlessly as did the AR and SIG rifles they were mounted on. They did not supress sound at all so there would be no legal issues to worry about...it would be just a very big flash hider...lol
Also had experience with some of MFI`s fake cans on HK USP 45 Tactical as well as HK Mark 23....again these are exceptional and functional fake silencers. They also make some for AR`s,etc.
here is a pic of the fake AAC cans
Blackout flash hider
M4 2000 in black/ SCAR in tan
Member of CGN`s (can`t recall name) "stash" upon arrival from AAC