This is a good question for Law Enforcement, and since I am not a LEO, I'll pose another use for the gun registration. A spouse bludgeons his partner, rendering her unconscious. A neighbor sees the husband running from the house with blood on his hands, leaving the door open. Neighbor calls 911, and police put out an APB, with the suspect being described as armed and dangerous, using information they grab from his motor vehicle license and the HPD gun registration database. Another instance where it can be useful is weapon theft. How many weapon owners remember the serial numbers of every gun they own. Without these numbers, how do you notify pawn shops? Duh, da gun was brown and had a bluish tint! In an active shooting, wouldn't it help to know whether the shooter possessed an automatic or semi-automatic rifle, vs. a .22 cal pistol? Suppose a hotel employee noticed that Stephen Paddock was checking into the hotel with 4 rifle cases. Don't you think that LVPD would have been interested in this information (that the man actually owned 24 weapons)? Alas, Nevada has no gun registration. Meanwhile the hotel had to settle $800MM in lawsuits.
You need to stop turning every argument into an All or Nothing at All proposition. Information has its uses to build a case. It does not have to be the smoking gun.
You need to stop drunk-posting..

I don't even know where to start.
If you aren't keeping a list of your guns' serial numbers, don't make it everyone else's duty to register so YOU have your numbers handy. That's not even close to a valid solution IMHO.
Every gun owner has the serial number of the guns they own recorded on SOMETHING. It might be a bill of sale (private or FFL sale), a receipt from a store, a picture, or even by contacting the seller (store, private seller, etc.). If that fails, you may have listed it on your homeowner's or renter's insurance inventory.
If the gun was stolen from a lockbox, safe, or other storage container, was it kept in the factory box it came in when you bought it? Guess what's normally on the inventory label of every gun case I have? The serial number. I keep all the boxes for every gun I buy -- pistol or long gun. Every box has all the nomenclature printed on a label for each gun.
Most responsible gun owners -- and homeowners in general -- record the serial numbers of high value items and keep them in a safe location. They may even have photos of all the items as well. That information can be useful in case ANYTHING of value is stolen, lost or destroyed and you need to file a loss claim under your policy.
As a matter of fact, it's recommended by the police departments that you etch/engrave some unique identifiable information in all of your valuables where possible, something that is more attention-getting than a factory serial number. I routinely put the last four of my social on all my tools and electronics. That way, if the crook removed the serial number sticker or places another one over it, the pawn shop owner will hopefully see there's an engraved number that matches my police report.
So, in short, a gun registry is NOT the only way to ascertain the serial number of a gun you need to report stolen, even IF you don't have them memorized.
In your hypothetical, you didn't say what the man bludgeoned the woman with. If it was with the gun, and the witness was able to describe it to the police, then no registry is needed to assume he's armed. They already know he was armed and may still be. All the registry will do is tell the police the man owns a gun, not if he's actually armed or not. Saying he's armed and dangerous without knowing he's armed is irresponsible. It could get the man killed unjustly if a cop overreacts based on your hypothetical description of him having a gun without any evidence.
As for an active shooting, how the hell are you going to do a database search to know the shooter has ANY guns registered in his name? Don't you need the active shooter's name first? And, more importantly, nobody is going to approach the shooter differently based on what weapons he has registered. First, how do you know WHICH weapon he brought if he owns several? Secondly, how do you know he's even using one of his own guns? He might have killed a relative and taken that person's AR-10, because he thought his AR-15 wan't going to be enough for his plans. In this instance, the registry gives you possible guns he may be using, but it in no way identifies the gun in use. In your mind, a Cop is going to care if the guy has a .357 magnum versus a Beretta 9mm? Are the tactics going to change between a Ruger 10/22 and a Mini-14?
Wait, you said "WHAT IF an employee noticed 4 gun cases," then proceeded to lament that it would not have helped because "no NV gun registration." What kind if twisted logic is that? If the employee reports the gun cases to LE, do you really think they are going to review the hypothetical registrations, see he only LEGALLY OWNS 4 LEGALLY REGISTERED .22lr rifles, and not bother to go check the cases out in person? There's no evidence what's in the cases. They could be borrowed, stolen or illegally purchased. None of those would then be in any registry. Hell, he might have found a great deal on gun cases, and they are all empty!
Did you join Mothers Demand Action recently? Because you sound exactly like them -- you think people intending to commit crimes will comply with gun registrations, and anyone with a registered gun should enjoy being treated like a suspect whenever someone has a "feeling" over seeing a gun case.
