I have a question as well that I think is pertinent to this thread in a way, but I've always wondered if say, the feds or local authorities launched an investigation into me or any private citizen, and they were just poking around for Intel for suspected wrongdoing or were suiting up for a raid, would they have the 4473 information at their disposal to see if they were storming into an armed household or are they only able to operate under the assumption of "subject is likely to be armed" or can they definitively see all your purchase records and say for instance " 4473 records indicate subject is known to have purchased 4 AR15's, 6 shotguns and a Glock 17, etc...."?
Not in most states. Consider that 4473s are in-store records that would have to be physically checked. Also, the background check information is just to determine if you're prohibited from purchasing a firearm and doesn't include details other than on you (you've been present when they've called that in often enough to know that they just provide your personal info and nothing on the gun). So, for most of us there's no other information available at the state level or higher. I can't speak to all states, but here in TN we use a state system TICS background check for prohibited status and that is purged by the next day if there isn't a delay or hold.
OTOH, if your state has a carry permit system, THAT can be easily checked online by LEs.
So, for the most part, there's nothing other than trying to look through 4473s sitting in local FFLs to get that info.