not sure where this 500 fps thing came from... Last time I read the memorandum it was 5.7J that is the upper limit between uncontrolled firearm vs controlled firearm.
5.7J would be something like 790~ fps with a .2
lower limit was 366 to be uncontrolled. below that is a replica which is a no go.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.