Childproof Handgun Act of 1999 - Amends the Brady Handgun Violence Prevention Act to prohibit a licensed manufacturer, importer, or dealer from selling, delivering, or transferring a handgun to anyone other than a licensed manufacturer, importer, or dealer, unless the handgun is childproof. Defines "childproof" as a handgun that incorporates within its design and as part of its original manufacture technology that: (1) automatically limits the operational use of the handgun; (2) is not capable of being readily deactivated; and (3) ensures that the handgun may only be fired by an authorized or recognized user.

Makes exceptions for: (1) the manufacture for, transfer to, or possession by the United States, a State, or a Federal, State, or local government department or agency of a handgun or the transfer to, or possession by, a law enforcement officer of a handgun for law enforcement purposes (whether on or off-duty); and (2) the transfer to, or possession by, a certified or commissioned rail police officer of a handgun for law enforcement purposes.

Prohibits a licensed manufacturer, importer, or dealer from selling, delivering, or transferring a handgun to any person: (1) other than a licensed manufacturer, importer, or dealer, unless the transferee is provided with a locking device for that handgun; and (2) unless the handgun is accompanied by a specified warning on a label affixed to the gun and on a separate sheet within the packaging, regarding proper locking and storage, penalties, and possession by minors, with the above exceptions.

Sets penalties for failure to provide for childproof handguns and for locking devices and warnings.

Directs the Attorney General to make grants to applicants that submit an application that meets specified requirements to reduce violence caused by firearms through the improvement of firearm safety technology, weapon detection technology, or other technology.

Authorizes appropriations.