Or be hacked and then distributed.

Or just makes it's way into the hands of thieves. When someone breaks into your home, they typically go after a few kinds of items: Electronics, tools, cash/silverware, and guns. All of which are high-value and easily sold/fenced. Imagine if you had a list of homes that could be sorted by number of profitable items and the street address. It'd be a thief's dream.

I'm not sure thieves would specifically target a home where the owner is clearly known to be able to defend such a theft with swift, lethal force.

They just wait until you leave for work, or are asleep.

https://www.youtube.com/watch?v=zQNmj2gSq6A

Response time for the police is usually on the order of tens of minutes. A friend lives in the country and called about a suspicious person and had a deputy show up 3.5 hours later. Thieves know this and will be in and out pretty quickly. They know where to look - under the mattress. In the refrigerator/freezer. In the nightstand. On the top shelf of the closet.

Ah, an obvious factor that I failed to consider (homeowner being absent), thanks.

Is this different from a thief "casing" your house to determine if you've purchased big ticket items? If their access to the information is logged (which I know isn't always going to be valid) and you're notified that a civilian accessed your gun inventory record, is that more or less problematic than someone who just watches your house every weekend for a few weeks after, say, Christmas, to see what large packaging you throw out without breaking down?

I'm reconsidering my opinion on public access, for certain, and I'm sincerely trying to be as informed on the caveats as best I can.

There's currently a problem with "package bandits" that cruise neighborhoods after the UPS and FedEx trucks have been through. They'll hop out of their car and grab your delivery off the front porch. So they don't even have to break-in to steal from you. :(

A fairly large and obvious difference is that around Christmas I can (and usually do) break up the cardboard boxes into smaller pieces, and put them inside my trashcan instead of just on the curb, so the fact that I got, say, a large tv is hidden.

This sort of database would not be opt-out.

Security by obscurity is not security at all.

The vectors for a loss of information are already out there - it wouldn't even have to be the big online gun shops. A list of ammunition/gun accessories/hunting supplies etc is probably sufficient to make a good guess for whether someone owns a firearm.

Obviously there is a possibility for a database loss if they tracked all gun sales, but considering the stat that 30% of households have a firearm and the many other possible associated data sets the risk seems minimal.

The very latest survey, released by Pew on August 26th, ups that to 44% of all households, see http://www.people-press.org/2016/08/26/opinions-on-gun-polic... for the executive summary and up in the right hand corner the full release with that number http://www.people-press.org/files/2016/08/08-26-16-Gun-polic... Survey size was a bit over 2,000, so if they got a good sample, which is getting harder and harder, it ought to be a solid number (most national political surveys are half that size, 1,000 is considered to be a minimum for any degree of accuracy).

That percentage goes up and down depending on people's willingness to admit that to a nosy surveyer; RKBA activists attribute this recent increase to the huge numbers of first time owners who haven't yet decided on a policy of discretion. Me, I wonder how many of us longer term owners have adopted a FU attitude in the presidential campaign with the starkest choice ever presented to us, excepting perhaps G. H. W. Bush vs. Dukakis, but Bush the father was much closer to total prohibitionist Dukakis, and in fact we're still living with his import bans....

You are of course right that a list of suspected gun owners could be generated in a whole bunch of ways, although I note that when it comes to online ammo dealers I've never seen a group of vendors who are faster in discarding their records of past sales.