Since you are in California here is the California Description out of the Law:
(1) A softnose or expanding projectile is a bullet designed to increase from its original diameter, commonly referred to as "mushrooming", and retain a significant part of its original weight upon impact with, or when...
Should Not use that Bullet for Hunting. It is illegal in most places. In Alabama "mushrooming ammunition" is how it is stated in the Hunting Regulations.