I wasn’t even aware that Washington registered handguns. From KHQ:

Washington residents are buying handguns too fast for police to keep up.

The state’s firearms database is months behind. The Department of Licensing began November with a backlog of about 106,000 pistol transfers to enter into the database used by city, county and state authorities to find owners of handguns that turn up during investigations.

According to the article, they’re still entering transfers from last March.