Gun Control & RKBA

First, you'd be relying on commercial enterprises like Cabelas and Walmart to collect personally identifying info, verify that it's correct, transmit it to the government and then not retain the information. All you get from all of that (assuming everything goes as planned) is the prosecutor's ability to add to any other evidence he has, "We have solid evidence that Mr Smith bought the bullet used in the murder." To be believable by a jury there would need to be some short interval between the purchase and the murder. A few hours would be rather strong, a few years OTOH wouldn't.

I wasn't thinking of anyone removing the bullets from the casings. Those that shoot larger calibers and shoot often will buy equipment to reload their spent cases. I spent several days reloading some .30-06 prior to an extended trip to an outdoor range. You remove the spent primers from the casing you collected, inspect and resize the cases, add powder and new primers and press a new bullet into each casing. Buying these items in bulk and saving your brass to reload can save you money. We favored 150 gr copper jacketed spitzers. Altering or obliterating the markings would be simple.

Consider this scenario. I shoot often and favor .22 lr since it's cheap and light. I buy a dozen bricks of 500 rounds each when they go on sale. I meet 2 friends at the range for some plinking. Friend #1 brings his 22 revolver and friend #2 brings a ruger 10-22 rifle. We all use the same small cheap ammo. Friend #2 runs out of ammo and I give him 2 50 round boxes from one of those bricks which I bought 5 months ago and tell him he's buying me lunch. He shoots most of one box and tosses the one full and other partial box into his range bag. He locks the bag in his trunk and we meet for lunch at a diner. Returning home that evening he drops his range bag in hes driveway and a box of that ammo falls out unnoticed. Anyone can grab the box. I don't see that this guy has done anything wrong and he shouldn't have testify in court that he may have lost a box of .22.