The ATF has removed the exemptions they previously had on smoke grenades and other devices commonly used by airsoft players, photographers, and others. I also wasn't aware that they banned civilian sales of simunitions. Government agents obviously don't want civilians training.
Link to the ATF letter: https://mrgunsngear.org/47KqcFi
Link to the ATF letter: https://mrgunsngear.org/47KqcFi