Actual text from CA DOJ web site
A semiautomatic, centerfire rifle that has the capacity to accept a detachable magazine and any one of the following:
A pistol grip that protrudes conspicuously beneath the action of the weapon.
A thumbhole stock.
A folding or telescoping stock.
A grenade launcher or flare launcher.
A flash suppressor.
A forward pistol grip.
A semiautomatic, centerfire rifle that has a fixed magazine with the capacity to accept more than 10 rounds.
A semiautomatic, centerfire rifle that has an overall length of less than 30 inches.
A semiautomatic pistol that has the capacity to accept a detachable magazine and any one of the following:
A threaded barrel, capable of accepting a flash suppressor, forward handgrip, or silencer.
(B) A second handgrip.
A shroud that is attached to, or partially or completely encircles, the barrel that allows the bearer to fire the weapon without burning his or her hand, except a slide that encloses the barrel.
The capacity to accept a detachable magazine at some location outside of the pistol grip.
A semiautomatic pistol with a fixed magazine that has the capacity to accept more than 10 rounds.
A semiautomatic shotgun that has both of the following:
A folding or telescoping stock.
A pistol grip that protrudes conspicuously beneath the action of the weapon, thumbhole stock, or vertical handgrip.
A semiautomatic shotgun that has the ability to accept a detachable magazine.