Washington prohibits any person from manufacturing, owning, buying, selling, loaning, furnishing, transporting, or having in his or her possession or under his or her control any: 1) machine gun; or, 2) any part designed and intended solely and exclusively for use in a machine gun.¹ It is also unlawful to convert a weapon into a machine gun, or to assemble or repair any machine gun.² However, it is an affirmative defense to a prosecution brought under this section that the machine gun, was acquired prior to July 1, 1994, and is possessed in compliance with federal law.³ Federal law requires machine guns to be registered with the Bureau of Alcohol, Tobacco, Firearms & Explosives (ATF), and generally prohibits the transfer or possession of machine guns manufactured after May 19, 1986.⁴

In Washington, all machine guns, or any part designed and intended solely and exclusively for use in a machine gun, to convert a weapon into a machine gun are declared to be contraband, and all peace officers and members of the armed forces are required to seize machine guns or machine gun parts.⁵

The state also prohibits any person, in the commission or furtherance of a felony, to discharge, menace or threaten another person with a machine gun.⁶

In 2018 Washington prohibited any person from manufacturing, owning, buying, selling, loaning, furnishing, transporting, or having in his or her possession or under his or her control “bump-fire stocks.”⁷ Bump-fire stocks, also known simply as bump stocks, are a type of firearm accessory that can significantly increase its rate of fire to function similarly to a machine gun. In October, 2017, a shooter used multiple bump stock devices in an attack on concert-goers in Las Vegas to perpetrate the deadliest mass shooting attack in modern history. Washington defines a “bump-fire stock” as “a butt stock designed to be attached to a semiautomatic firearm with the effect of increasing the rate of fire achievable with the semiautomatic firearm to that of a fully automatic firearm by using energy from the recoil of the firearm to generate a reciprocating action that facilitates repeated activation of the trigger.”⁸

 See our Machine Guns policy summary for a comprehensive discussion of this issue. 

1. Wash. Rev. Code Ann. § 9.41.190(1).[↩]
2. Id.[↩]
3. Wash. Rev. Code Ann. § 9.41.190(3).[↩]
4. 18 U.S.C. § 922(o); 26 U.S.C. § 5861(d).[↩]
5. Wash. Rev. Code Ann. § 9.41.220.[↩]
6. Wash. Rev. Code Ann. § 9.41.225.[↩]
7. Wash. Rev. Code Ann. § 9.41.190(1).[↩]
8. Wash. Rev. Code Ann. § 9.41.010(3).[↩]