Senate Bill 23, authored by Senator Don Perata, was signed by Governor Gray Davis on July 19, 1999, and took effect on January 1, 2000.[1] SB 23 closed the primary loophole in the Roberti-Roos Act by defining assault weapons based on physical characteristics rather than make and model, ensuring that functionally identical firearms could not evade regulation simply by using a different name.
The Characteristics Test
SB 23 added what is now Penal Code Section 30515, which classifies a semiautomatic firearm as an assault weapon if it meets specific feature combinations:
- Semiautomatic centerfire rifle with detachable magazine plus any one of: pistol grip that protrudes conspicuously beneath the action, thumbhole stock, folding or telescoping stock, grenade or flare launcher, flash suppressor, or forward pistol grip
- Semiautomatic centerfire rifle with fixed magazine capacity exceeding 10 rounds
- Semiautomatic centerfire pistol with detachable magazine plus any one of: threaded barrel, second handgrip, barrel shroud, or capacity to accept a magazine outside the pistol grip
- Semiautomatic shotgun with folding or telescoping stock, pistol grip, detachable magazine, or fixed magazine exceeding 6 rounds
Registration Period
Owners of firearms meeting the new characteristics test definition were given until December 31, 2000, to register them with the DOJ as assault weapons.[2] After registration closed, unregistered firearms meeting the definition became illegal to possess. Registered firearms are subject to the same restrictions as Roberti-Roos registered assault weapons.
Compliance Pathways
Because the characteristics test hinges on the combination of a detachable magazine plus prohibited features, two primary compliance strategies emerged:
- Featureless build: Remove all prohibited features (use a fin grip or Thordsen stock instead of a pistol grip, pin the stock, remove flash hider) while keeping a standard detachable magazine release. This approach preserves normal magazine changes but alters the ergonomics of the firearm.
- Fixed magazine: Install a magazine lock device that requires separation of the upper and lower receivers (or equivalent disassembly of the action) to release the magazine. This allows retention of all prohibited features but significantly slows magazine changes.
Bullet Button Era (2000-2016)
From 2000 to 2016, the DOJ interpreted "detachable magazine" to mean a magazine removable without use of a tool. The Bullet Button, a device requiring a bullet tip or small tool to press the magazine release, was initially accepted as making the magazine non-detachable. SB 880 and AB 1135 (2016) redefined "fixed magazine" to require disassembly of the firearm action, effectively banning the Bullet Button compliance strategy as of January 1, 2017.