It says CL04 on the bottom the cartridge lenght is 2 1/2" long.I don't have a point of reference, for the cartridge length. That would help greatly.
I'd guess, 7.62 or 308. but a length would be helpful. Do they have any numbers or words on the base of the shell?
Looks more like a 30-06 to me. If you know someone who reloads any 30 cal. ammunition they'll have a sizing die that will work.They look like NATO cartridges, about the same as .308. These are blank rounds, you will need a sizing die to remove the crimp from the bullet end.
Those look like the ones that I have to make some pens out of. Same deal. Military funeral salute. What caliber did you find out they are?