I’m lead to believe that the author of this article left off a bunch of zeros:
Capt. Troy Balcar of the San Antonio Fire Department said a family member found a sealed box with about 75 rounds of decades-old ammunition underneath the house. He said the rounds were about 40 years old, based on a date written on the box. Half a dozen nearby homes were evacuated for about three hours.
Perhaps the author meant 7,500,000 rounds of ammunition? Honestly, I’d expect less overreactions from Texas than this. That state seems to have its head mostly screwed on right when it comes to firearms.
Ammo outside of a gun is so ineffectual it cannot even penetrate firefighter bunker gear at more than a foot except in very large caliber pistol and large caliber rifle rounds. And even then old ammo does not just go off the problem is usually the opposite.