CA AB1664

Revises the definition of "assault weapon" to include semiautomatic centerfire rifles and pistols that lack a fixed magazine and have specified attributes such as thumbhole stocks, folding stocks, or second handgrips.

Defines "fixed magazine" as an ammunition feeding device contained in or permanently attached to a firearm that cannot be removed without disassembly of the firearm action.

Requires persons who lawfully possessed assault weapons without fixed magazines between January 1, 2001 and December 31, 2016 to register them with the Department of Justice by January 1, 2018 through an online application, with a registration fee of up to $15 per person.

Exempts from prosecution persons who possessed assault weapons prior to January 1, 2017 if they register the weapon by January 1, 2018 and meet specified eligibility requirements.

Becomes operative only if Senate Bill 880 of the 2015-16 Regular Session is enacted and takes effect on or before January 1, 2017.