Anti-Walk pins serve no purpose if your pins are walking you have your parts installed incorrectly as the trigger and hammer and j springs lock the pins in place.
Washington state law says the following.
RCW 9.41.220
Unlawful firearms and parts contraband.
All machine guns, short-barreled shotguns, or short-barreled rifles, or any part designed and intended solely and exclusively for use in a machine gun, short-barreled shotgun, or short-barreled rifle, or in converting a weapon into a machine gun, short-barreled shotgun, or short-barreled rifle, illegally held or illegally possessed are hereby declared to be contraband, and it shall be the duty of all peace officers, and/or any officer or member of the armed forces of the United States or the state of Washington, to seize said machine gun, short-barreled shotgun, or short-barreled rifle, or parts thereof, wherever and whenever found.
[1994 sp.s. c 7 § 421; 1933 c 64 § 4; RRS § 2518-4.]