Using data from 140 interviews with individuals detained in the Los Angeles County Jail system, this article examines what gun offenders know about gun and ammunition regulation in California. Though most respondents had a consistent, albeit general, understanding of the regulations limiting gun acquisition and possession, analysis suggests that their understanding of ammunition restrictions was more limited. Our sample’s awareness of firearms law is especially important to consider given that they are the very population targeted by firearms regulations and prohibitions at the local, state, and federal level. By examining what detained offenders know about firearms laws, we can better theorize about individual gaps in legal knowledge and the realistic expectations for how understanding of the law can affect behavior.