Wash. Rev. Code § 9.41.140
No person may change, alter, remove, or obliterate the name of the maker, model, manufacturer's number, or other mark of identification on any firearm. Possession of any firearm upon which any such mark shall have been changed, altered, removed, or obliterated, shall be prima facie evidence that the possessor has changed, altered, removed, or obliterated the same. This section shall not apply to replacement barrels in old firearms, which barrels are produced by current manufacturers and therefor do not have the markings on the barrels of the original manufacturers who are no longer in business. This section also shall not apply if the changes do not make the firearm illegal for the person to possess under state or federal law.
RCW 9.41.140
Finding-Intent-Severability-1994 sp.s. c 7: See notes following RCW 43.70.540.
Effective date-1994 sp.s. c 7 ss 401-410, 413-416, 418-437, and 439-460: See note following RCW 9.41.010.