The more I read about preban and postbans the more I'm convinced that it is almost impossible for you to get caught modifying your post ban.
Nobody knows what is or isn't legal. Most gun stores and cops don't even know.
And how can the cops tell if they need to run the serial number to find out when it was made.
Throw on top of that the "legal clone features" like look a like flash supressors, look a like stocks, etc. etc.
Plus who the heck checks guns anyway? Name one situation where your gun would be taken and checked out if you weren't already breaking the law? I'm sure there are some, but I can't think of any.
Now don't get me wrong, the last thing I need or want are grenade launchers, bayonettes or even flash supressors, but it doesn't seem like anyone would ever get caught or care. Do the cops really want to bust some guy with a flash suppressor?