Don’t know about WA. How do they know you have an “AR”?
Do you need more paper than the 4473?
The Fed 4473 will tell, but some are still in dealers hands and the Feds don’t have them (yet). Feds could trace from manufacturers to WA dealers, then trace some more. But can the state do that?
Anyway, this is no mistake, just a conditioning of the population to accept it.
PS, In Calif, if grandfathered in, they KNOW.
I'm sure rumors from your irate neighbors would be sufficient.