i think for most states there is a law on how many fps your gun can be, i think for indiana its 430 or something
I'm pretty sure that there are no official laws restricting FPS but, most game organizers set an FPS limit.
Most common is 400 FPS cap for all guns excluding snipers, engagement distance limit is most commonly 10-20ft for AEGs, 100ft for snipers, and 5ft-10ft for pistols. In most games, snipers are cap'd at 500 FPS.
For your gun to count as a sniper, it needs to be semi-auto only and be an actual sniper, not some M4 Variant.
In most games you also can only use mid-caps with your guns but, alot of game organizers allow hi-cap box mags for LMG guns.
i got a 600 fps cast iron and oak m1a1 Thompson submachine gun. full auto.
I call bullstuff, even if you do, I doubt you'll be able to use it in any games.