It is impossible for anyone to legally own any firearm silencer in the USA without it being registered with the ATF. This includes dealers, police and military.
There are a few states that have passed laws to regulate various firearms (including silencers) and exempt them from registration (and the $200 tax) with the ATF. But the feds are opposed to these laws and the ATF has warned licensed dealers that they still have to comply with the registration requirements. As far as I know, the law has not been tested in court.
Bills 1016 and 5112 only affect Washington State. All the bills do is allow the use of any registered firearm silencer. Use of an unregistered silencer would still be illegal and result in a $5000 fine and a year in jail in addition to the much more severe federal penalties which start with a $10,000 fine and 10 years in prison for evading the tax and registration requirements.
WA State has no registration requirements for silencers. The only mention of them in the WA code is to ban their use on a firearm.