Most AR-15 parts are no longer legal to buy in Washington State. Since April 2023, state law has banned the sale, import, and distribution of assault weapons and the parts used to assemble or convert a firearm into one, and AR-pattern rifles are named directly in the statute. General accessories like optics, slings, cases, and cleaning supplies remain legal to purchase. Receivers, conversion kits, standard-capacity magazines, and the specific feature parts that define an assault weapon under the law are not.
AR Parts You Cannot Buy in Washington
RCW 9.41.390 prohibits anyone in Washington from manufacturing, importing, distributing, selling, or offering for sale an assault weapon, and it extends that prohibition to any conversion kit, part, or combination of parts from which an assault weapon can be assembled or a firearm converted into one, if those parts are in the same person’s possession or control. The AR-15, M16, and M4 “in all forms” are listed by name.1State of Washington 68th Legislature. House Bill 1240
Lower Receivers and Frames
The lower receiver is the clearest prohibited part. The statute defines a frame or receiver as the part that provides housing or structure for fire control components when the firearm is assembled.1State of Washington 68th Legislature. House Bill 1240 An AR-15 lower is the serialized component the entire rifle is built around, so its sale or import falls squarely inside the ban.
Feature Parts That Define an Assault Weapon
Washington treats a semi-automatic centerfire rifle with a detachable magazine as an assault weapon if it has even one of several listed features. Parts that supply those features are off limits because combining them with other AR components produces exactly what the statute prohibits. The restricted features include:
- Flash suppressors, flash hiders, flash guards, flash eliminators, sound suppressors, silencers, and similar devices designed to reduce visual or audio signature.
- Muzzle brakes, recoil compensators, and other devices that attach to the barrel to reduce recoil or muzzle rise.
- Threaded barrels designed to accept a flash suppressor, sound suppressor, or muzzle brake.
The same feature test applies to semi-automatic pistols with detachable magazines, where threaded barrels capable of accepting a flash suppressor, forward handgrip, or silencer are specifically called out.2State of Washington Legislature. House Bill 1240 (PDF)
Unfinished Receivers and 80% Lowers
A separate statute, RCW 9.41.326, closes the unfinished-receiver route. Since March 10, 2023, it has been illegal to manufacture, assemble, possess, sell, or purchase an untraceable firearm in Washington unless you are a law enforcement agency or federal licensee.3Washington State Legislature. RCW 9.41.326 – Untraceable Firearms Exceptions Penalties Narrow carve-outs exist for antiques, firearms made before 1968, permanently inoperable guns, and unfinished frames properly serialized by an authorized federal licensee. An 80% lower bought as a build project falls outside those exceptions.
Standard-Capacity Magazines
Any ammunition feeding device holding more than 10 rounds qualifies as a large capacity magazine under RCW 9.41.370, and the manufacture, import, distribution, and sale of those magazines was banned in 2022.4Washington State Legislature. Washington Code 9.41.370 – Large Capacity Magazines Exceptions Penalty Standard 30-round AR magazines cannot be purchased from a Washington gun shop or shipped in from out of state.
AR Parts You Can Still Buy
Plenty of general-purpose gear is unaffected. Optics, red dots, slings, cleaning kits, cases, ammunition (subject to any applicable purchase requirements), and similar accessories remain legal to buy. The test the statute applies is whether a part is used to build or convert a firearm into something meeting the assault weapon definition. A scope on a shelf is not a prohibited component. A flash hider sitting in the same gun safe as a stripped lower may be.
If you own firearms that fall outside the assault weapon definition entirely, buying replacement parts and accessories for those guns is not affected by the 2023 law.
Ordering Parts From Out of State or Online
Buying prohibited parts from a seller outside Washington and having them shipped in is illegal. The statute lists “import” among the prohibited activities, and the Attorney General’s office defines import as moving, transporting, or receiving an item from outside Washington’s borders to a place inside the state.5Office of the Attorney General. Firearms FAQ Online orders are covered. It does not matter whether the seller operates in a state where the parts are legal; the person receiving the shipment in Washington is the one violating the law.
There is one narrow travel exception. If you leave Washington with an assault weapon or large capacity magazine you already legally own, you can return with that same item without the re-entry counting as a new import.5Office of the Attorney General. Firearms FAQ You cannot leave the state, buy new prohibited parts, and bring them back.
What About Repairing an AR You Already Own
Possession of an AR-pattern rifle you legally owned before April 25, 2023, is still allowed; the legislature intended to restrict future sales rather than take existing firearms away.1State of Washington 68th Legislature. House Bill 1240 Replacing a worn part on that rifle is harder than it sounds, because the ban on selling and importing assault weapon parts has no broad repair exemption for pre-ban owners.
The one explicit repair provision is narrow: a person who inherits an assault weapon after the original owner’s death may transfer it to a federally licensed gunsmith for service or repair.6Washington State Legislature. RCW 9.41.390 – Assault Weapons Manufacturing, Importing, Distributing, Selling Prohibited Exceptions Penalty The statute does not clearly extend that same gunsmith exemption to people who bought their firearm before the ban rather than inheriting it. Talking to a Washington firearms attorney before buying any replacement part for a grandfathered rifle is the safer path.
Penalties for Buying Prohibited Parts
Violating the assault weapons ban is a gross misdemeanor.6Washington State Legislature. RCW 9.41.390 – Assault Weapons Manufacturing, Importing, Distributing, Selling Prohibited Exceptions Penalty The maximum sentence is up to 364 days in county jail, a fine of up to $5,000, or both.7Washington State Legislature. RCW 9A.20.021 – Maximum Sentences for Crimes Committed July 1, 1984 A conviction creates a permanent criminal record that can affect employment, housing, and future firearm rights.
Buying an unserialized lower or a standard-capacity magazine triggers separate penalties under the untraceable firearms and large capacity magazine statutes, so a single transaction can stack multiple charges.