According to the National Shooting Sports Foundation (NSSF), California consumers buy about 1.2 billion rounds of ammunition annually, about 12% of the total U.S. market. While some of this is rifle ammunition, there’s some vagary in the new law which may result in rifle ammunition purchasers being included under the new law:
Where ammunition or reloaded ammunition may be used in both a rifle and a handgun, it may be sold to a person who is at least 18 years of age, but less than 21 years of age, if the vendor reasonably believes that the ammunition is being acquired for use in a rifle and not a handgun.
This reasonability test creates a gray area, and considering California’s anti-rights history, any doubts will likely side towards the seller requiring your personal information. For example, people with .22 rifles may have to register, because of all the .22 target pistols that fire the same rounds.
Bottom line: If rifle owners believe they have somehow escaped unscathed, they are only fooling themselves. Also, there is nothing stopping the legislature from revising this law to include all ammunition in the future.