I can't find an email for the author, so I just posted this on KHON's facebook page.
If this was for 1 round of ammunition, then this isn't really a news story and TSA overacted. 50 caliber ammunition is allowed in check-in bags as long as it's not loaded into a firearm, packaged correctly, is .75 caliber or less, and is limited to a total of 11lbs or less by most airlines. Normally if there's an issue TSA would stop the bag, inform the owner, discard the item if necessary, and continue on as normal.
The danger from ammunition is from potential fire. No more dangerous than lithium batteries, flammable aerosols, and other controlled items.