I know Maryland has rules and restrictions and you must register the powder you buy so the Fire Marshall can check. Who knows what California requires??
I am not a lawyer and therefore not YOUR lawyer
I have read Florida Gov't Statutes for years and stayed in a Holiday Inn Express
http://www.leginfo.ca.gov/cgi-bin/displaycode?section=hsc&group=12001-13000&file=12101-12112
12102. This chapter does not apply to any possession or use of 20
pounds or less of smokeless powder, or one pound or less of black
sporting powder, provided that:
(a) Smokeless powder is intended only for hand loading of small
arms ammunition of .75 caliber or less.
(b) Black sporting powder is intended for loading of small arms or
small arms ammunition of .75 caliber or less.
(c) All such powder is for private use and not for resale, and, in
the case of black sporting powder, there shall be no gift, delivery,
or other disposition to another person.
(d) The storage, use and handling of such smokeless and black
powder conforms to rules, regulations, or ordinances of authorities
having jurisdiction for fire prevention and suppression in the area
of such storage, use, and handling of such explosives.