Blank Ammo Question

Someone will want them. Ceremonial or for movies. Or maybe a cartridge collector. Depending the headstamp and type of blank, they also may know where there is a market.
For use with a non-bolt action they need to be used with the matching blank adapter.
This guy successfully sold some.
FS: 5.56 & 30.06 Blanks - CMP Forums

Blank adapters - CMP Forums