I will mention a potentially worse problem. The brass was not discarded or (AFAIK) used by anyone else, but it could have been.
I watched a man at the range firing an M1A. Every shot, the case stuck in the chamber, and several primers fell out of the primer pockets. Finally, I asked him what was happening, and he said it had just started happening after he annealed his cases, like the gun magazine said. Suspicious, I asked how he annealed the cases, and he told me he used a plumbers blowtorch to heat them red hot all over and then let them cool down. That brass must have been soft as lead.
I told him what he was doing wrong, and "suggested" rather firmly that he crush the brass and throw it away where no one would pick it up. He refused, saying that he couldn't afford to buy another 20 rounds and he planned to continue to reload those cases! I just hope he had an alert guardian angel.
But if he had left those cases lying on the range to be picked up and reloaded, someone else could have been seriously injured.