text:  A new gun law takes effect tomorrow in California that will require credit card networks to provide banks with special retail codes to assign to gun stores. Advocates say it will help the state track sales to flag suspicious purchases and possibly avert mass shootings. The opposite happening this week in at least four states, though. Georgia, Tennessee, Iowa, and Wyoming. A total of 17 states have now passed limits on category codes for retailers. Monica Ricks, CBS News.