That tax was just an end run around the gun laws by the city of Seattle. It was just to drive out pro 2A storefronts. Don't fall for the rhetoric that it was to fund money for gun studies. California is trying to do the same thing with the ammo taxes, AW registry, handgun roster, no online ammo purchases and micro-stamping idiocy.
I lived there for 11 years and it was bad 20 years ago. Seattle's hardcore, progressive mandate has caused so much damage over the years it won't really matter if they adopt California-style gun control.
It's the people that are lost, the government is just a reflection of the people.