I am sure most guns have been lost in tragic boating accidents. And who could remember those bought in private sales years ago. Those oficially tracked through background checks are already targeted for a future confiscation regardless what the retainment of Background Check records law says.
The supply is opening up some here. I was at a smaller shop who had quite a selection of better AR-15s and Ar-10s in stock.
Had ATF come to my door and seize a semi-collectible revolver purchased two years and 6 states away from my current location. The gun had been reported stolen in 1996 in Kansas. Person reporting the theft had died and gun went to his heir. I had no recourse nor could I question the original report. Since then I have made a point of selling or trading new purchases to people known to be of good character or possessing a valid concealed carry permit. Too bad my gun safe was swallowed up in a sinkhole - never got the chance to take them boating.