Must be for pistol cartridges then. I don’t know. There are rifle cartridges with bigger than 0.5”
My Fathers Day goodies were 4 bullet comparison posters for Handguns, Big Bores, Rifles and Military cartridges. 1:1 scale pictures of each type....neat. Looking for the poster sleeves now.
If you read through the search warrant he used straw buyers to purchase AR15s and made booby traps which consisted of a 12ga shell in a pipe.
I didn’t make it all the way through so there may be more.