RCW 9.41.240: Possession of pistol or semiautomatic assault rifle by person from eighteen to twenty-one.

(1) A person under twenty-one years of age may not purchase a pistol or semiautomatic assault rifle, and except as otherwise provided in this chapter, no person may sell or transfer a semiautomatic assault rifle to a person under twenty-one years of age.

(2) Unless an exception under RCW 9.41.042, 9.41.050, or 9.41.060 applies, a person at least eighteen years of age, but less than twenty-one years of age, may possess a pistol only:

(a) In the person's place of abode;

(b) At the person's fixed place of business; or

(c) On real property under his or her control.

(3) Except in the places and situations identified in RCW 9.41.042 (1) through (9) and 9.41.060 (1) through (10), a person at least eighteen years of age, but less than twenty-one years of age, may possess a semiautomatic assault rifle only:

(a) In the person's place of abode;

(b) At the person's fixed place of business;

(c) On real property under his or her control; or

(d) For the specific purpose of (i) moving to a new place of abode; (ii) traveling between the person's place of abode and real property under his or her control; or (iii) selling or transferring the firearm in accordance with the requirements of this chapter; provided that in all of these situations the semiautomatic assault rifle is unloaded and either in secure gun storage or secured with a trigger lock or similar device that is designed to prevent the unauthorized use or discharge of the firearm.