A guy on another forum payed i think around 10k for an M16 , it took him at least 4 months to get his paperwork back.
He then said you better have deep pockets for the ammo it uses ,and it wasn't all that accurate.
I wouldn't even think about messing with anything ;like this with out doing it by the book , you couldn't shoot it without looking over your shoulder all the time.
It just isnt worth it at all , LEOs are up on this stuff ,they are not ignorant to the laws. If you even own the gun ,and the parts separate its still a crime ,it shows intent.
You haven't gained as much as you think eiather , i sold both of my Class 3, FAs in 1994 , to a Sheriffs Dept. in Texas.
I never missed them , accuracy is more important to me , i would rather have the AR15 with a good sight than to spray and pray.
Ammo is far to precious a commodity now to waist it .
Lloyd is right ,you cant own a Class 3 made after 1986 unless you are a dealer with post samples ,or LE or Millitary.
This is why you see LE agencys buying NIB MP5s for $650.00 , a worn out one to you can be as high as 10k easily.
This is why a lot of guys only buy the sear , if you bought the sear for an H&K ,it could go between any H&K you owned because the sear has the Ser#.