I live in Bellingham. H&H Sporting Goods has common ammo. They also sell rifles and handguns.
Kesselring, about 10 miles south of Bellingham on old Hwy 99 is the mecca for gun stuff. They have a huge supply of guns, ammo, reloading supplies, etc.
As far as I know, there are no restrictions on ammo purchases. Just go in and buy it.
pm me if you have more questions.
-terry