A firearm magazine can hold several rounds of ammunition and is detachable from the firearm.  Washington law does not impose regulations relating to ammunition or ammunition magazines, aside from a requirement that firearms dealers must obtain a license to sell ammunition.  In 1994, Congress enacted a ban on the manufacture, transfer, and possession of assault weapons and large capacity ammunition feeding devices capable of holding more than ten rounds of ammunition, but exempted assault weapons and large capacity ammunition feeding devices that were manufactured before the law became effective.  This law was subject to a sunset provision and expired in 2004.

Nine states and the District of Columbia have enacted laws that prohibit or place restrictions on large capacity magazines, typically defined as magazines capable of accepting more than ten or 15 rounds of ammunition.  Some of these state laws completely ban the manufacture, transfer, or possession of large capacity magazines, while others exempt large capacity magazines that were possessed prior to the law's effective date. 

Gross Misdemeanors.  Every person convicted of a gross misdemeanor defined in law shall be punished by imprisonment in the county jail for a maximum term, fixed by the court, up to 364 days, or by a fine, in an amount fixed by the court, of not more than $5,000, or by both.

A large capacity magazine is defined as an ammunition feeding device with the capacity to accept more than 10 rounds of ammunition, or any conversion kit, part, or combination of parts, from which such a device can be assembled if in the possession of the same person.  A large capacity magazine does not include:

• an ammunition feeding device that has been permanently altered so that it cannot accommodate more than 10 rounds of ammunition,
• a 22 caliber tube ammunition feeding device, or
• a tubular magazine that is contained in a lever-action firearm.

Distribute means to give out, provide, make available, or deliver a firearm or large capacity magazine to any person in this state, with or without consideration, whether the distributor is in-state or out-of-state.  Distribute includes, but is not limited to, filling orders placed in this state, online or otherwise.  Distribute also includes causing a firearm or large capacity magazine to be delivered in this state.

Import means to move, transport, or receive an item from a place outside the territorial limits of the state of Washington to a place inside the territorial limits of the state of Washington.  Import does not include situations where an individual possesses a large capacity magazine when departing from, and returning to, Washington State, so long as the individual is returning to Washington in possession of the same large capacity magazine the individual transported out of the state.

A person may not manufacture, import, distribute, sell, or offer for sale any large capacity magazine except as specifically authorized.  

The ban does not apply to the manufacture, importation, distribution, offer for sale, or sale of a large capacity magazine:

• by a licensed firearms manufacturer for the purposes of sale to any branch of the armed forces of the United States or the state of Washington, or to a law enforcement agency in this state for use by that agency or its employees for law enforcement purposes;
• by a dealer that is properly licensed under federal and state law for the purpose of sale to any branch of the armed forces of the United States or the state of Washington, or to a law enforcement agency in this state for use by that agency or its employees for law enforcement purposes; or
• by a dealer that is properly licensed under federal and state law where the dealer acquires the large capacity magazine from a person legally authorized to possess or transfer the large capacity magazine for the purpose of selling or transferring the large capacity magazine to a person who does not reside in this state.

A violation is a gross misdemeanor offense.