Ever fill out a Form 4474?
Chances are, your guns have been registered in a DB somewhere where the LEOs have “conveniently forgotten” that it’s illegal for them to do so — also, I wouldn’t put it past them to track ammo & reloading-related purchases as well.
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My last gun purchase was in early 1980s. No forms to complete and no background checks here at that time.
Too bad about that canoeing accident.