[JimDandy]

That's a very myopic view.
Here's how it works: You collect 'infinite' amounts of data, catalogue it, tree it, cross reference it, spider it, then sit on it until you need actionable intelligence, leverage or something else.

Yeah, but what data can they hoover up? Gun shops still operate under a very archaic, non-digital system in which paper records are kept in an arbitrary order on the premises. Finding one guy's information is like finding a needle in a very big haystack.

There's the phone call. The E-form. Gunbroker, Armslist, and so on. More than they should. But again, they'd still need a reason to stick a warm body in front of a keyboard to look at it. Which isn't likely to come from a trip to the store in and of itself.

So what you're saying is they passively collect a bunch of stuff about you or I, and sit on it (catalog), until you come to their attention for something they care about (need actionable intelligence). Gee. Sounds pretty much like what I said, so I guess we're both myopic

Yes they do. They collect all the data they can get their hands on, index it by whatever criteria, and then just store it away.

That is passively tracking. To put a warm body on the screen looking at Joe from Anytown, USA day in and day out is actively tracking.

Let's for a second consider the sheer number of credit card transactions that occur at retail every day. Even if they had a surveillance program to tap that, it would have to work transparently with dozens of payment processing companies, all running several different types of hardware and operating systems.

This is certainly accurate. It's also not the way the NSA would track gun sales. A credit card slip doesn't say what you bought. It just says you spent XYZ dollars at ABC location. They'd transcribe the 4473 phone call. Name, description, long gun/pistol it's all there. And they still wouldn't be 100% accurate doing that. They wouldn't know which ones were gifts, which ones you sold later to the guy who's back yard adjoins your back yard, and so on.

Could they ever create a gun registry? Probably not.

Sure they could. A couple states already have, without the NSA. If the Feds wanted to, the NSA would not be the agency they use. Congress would pass a law reclaiming all the bound books, require a voluntary-ish registration from everyone, and then start tracking all the transactions, for the basics. Hope you kept a copy of the receipt and possibly ID of any second hand sales you made.

Imagine they learn that you don't have a CWL but you bring your gun from your apartment to your car where it's illegal in your state because you want to protect yourself. That you bought a gun and removed the permanent flash hider and the barrel length ended up being 15.8". You're looking at felonies there for laws you might not even know existed.

Both of those examples are more likely caught by a LEO/Citizen seeing you, than an email sucked up by the NSA. And both of those are "your" fault, much more so than performing websearches by multiple family members for backpacks, a pressure cooker for your quinoa, and news on the Boston Bombing.