Police rely heavily on databases when looking into gun ownership. Under the new bill, police would be forced to directly contact gun manufacturers in order to obtain gun ownership information. Time is a critical component when investigating crimes, especially those involving guns.
...and then Jeff goes on to fret about manufacturer warranty cards. Except that, contrary to the anonymous editorializer, police do not rely on databases, calling the manufacturer, warranty cards, or anything like that.
When the police get their hands on a gun used in a crime, who they call is the BATFE, not the manufacturer. The BATFE turns to its National Tracing Center and gets the ball rolling. Let's say the gun in question is a Blastomatic Euroshooter 2000, serial number XYZ123. The NTC would call Blastomatic USA, Inc. and inquire as to the disposition of gun XYZ123. Blastomatic would consult its records which, according to the Gun Control Act of 1968, it must maintain for twenty years. It determines that the gun was sold to The Very Big Sports Wholesale Co. back in February of 2006, and informs the NTC of this. The NTC then contacts The Very Big Co., who tells them that the gun was shipped to Billy Bob's House of Blasters in November of '06. (Slow selling model...)
Now Billy Bob's gets a call. The person at Billy Bob's who handles their log books (which, remember, must be maintained for twenty years) looks up the gun in question, and relays to the NTC operator that gun #XYZ123 was sold to a Mr. John Doe on March 25, 2007. Finally, John Doe is going to get a call. This is why it's good to keep a Bill of Sale if you sell a "papered" gun to a stranger.
Federally licensed firearms dealers are usually only too happy to check that serial number. The NTC isn't used to check and see if a gun is stolen; the cops can do that via the National Crime Information Center, usually using the laptop in their squad car. The NTC is used when a mysterious gun is found in relation to a crime; sometimes in the vicinity of a cooling body. If I can help get to the bottom of something like that, well, I'm all about it.
As you can see, no warranty cards were consulted in this production, so go ahead and fill them out or not as you please, but understand why you're doing it.
In the comments section, someone then (predictably) mentioned Using Credit Cards At The Gun Store. I know that in Tom Clancy productions and William Gibson-esque dystopian futures, when you use a credit card, it "sends up a flare in cyberspace" and some government console jockey or rogue hacker squinting at a screen yells "We got him, boss! He just bought a used Glock and 500 rounds of 9mm ammunition at Joe's Hunting Shack using his Visa card!"
Except it doesn't work that way. If they were so hot on your trail that they were actively monitoring your financial activity, at best they'd know that you spent $599.78 at Joe's on April 30th at 5:39 PM. For them to discover whether you were buying a Glock or a shotgun or a tree stand or annual range memberships for your golfing buddies or a gift certificate for your mom is going to require a warrant and a trip to the shop in meatspace. All Joe did is punch a dollar figure into a credit card terminal; the bank hasn't a clue what that money was spent on.
Gun shop owners and personnel tend to be a conservative lot, in the classic definition of the term. A surprising number are still uncomputerized in this day and age, and even those of us who are are going to want to see a warrant or a subpoena before we divulge any customer information of that nature. I also suspect that any nation-wide demand for that data en masse for some kind of National Registration scheme would see a rash of hard drive failures from coast to coast. Pesky Windows always was unreliable, you know.