The AG’s office plans to file a lawsuit blocking a website from disseminating digital firearm files.
Gun rights groups have threatened legal action over the measure.
Initiative 1639 would require something similar on paperwork for firearms purchases.
A ballot initiative could restrict semi-automatic weapon sales, including raising the purchase age to 21.
Thousands of demonstrators gathered together in Seattle on Saturday to demand safer schools.
The device that increases a gun’s rate of fire has been used in mass shootings.
