it's fairly easy to predict that this law will result in few solved cases, if any
The shooting industry will probably simply refuse to produce new firearm models with this feature. Consequently, Californians will not have the chance to buy these new models.
And exactly why should the manufacturers desire to produce a new model with a feature that would limit sales? Many shooters would avoid this firearm like a plague.
Smith and Wesson revolvers are currently manufactured with a key operated safety lock.

This feature has caused many customers to avoid purchasing new S&W revolvers. Gun forums have discussed incidents when this feature has locked the gun accidentally and prevented it from firing. One member of the range I used to shoot at, stated that he had this happen while he was shooting. Indeed, the firearm was locked. I used my S&W key to unlock it as he didn't have his key with him. He had no further problems that day, but said that he planned to sell, "this fucking useless piece of shit!" Note: I personally have had no problems with the lock on the revolvers I own. Still, my prime carry revolver is pre-lock.
Many people who buy new S&W revolvers disable the safety lock. Many just buy used pre-lock S&W revolvers.
I would suggest that the new law is just an attempt by politicians to stop the sale of new semi-auto firearms in California. Coupled with their draconian new law that deals with the purchase of ammo, they hope to legislate new firearms out of existence and make ammo more expensive and hard to purchase.
Starting February 1st, 2011 handgun ammunition vendors will be required to obtain a thumb fingerprint and driver's license from buyers. One firearms dealer we spoke to in town said criminals will find another way to get their bullets.
To buy ammo in California a vendor only needs proof of age. But that has changed. In a year and a half a new law will require vendors like Bill Mayfield to keep track of all handgun ammunition sales. The goal is to better track the bullets used in crimes, but Mayfield said it won't work.
Mayfield said, "You're gonna force every law abiding citizen to go through paper work that these people won't. The gang-banger, 90% of what their using is probably stolen in the first place."
The new law also states ammunition must be safely stored behind the counter and sales made face to face. Mayfield warned he will have to raise his prices.
***snip***
Any violation of this new law and the offender faces a misdemeanor charge. Because all transactions must be face to face that means sales on-line must cease.
http://www.democraticunderground.com/discuss/duboard.php This idea of registering all purchases of handgun ammo was tried years ago at a federal level and failed miserably. All that was accomplished was the depletion of enormous forests to provide the paper.