Apologies, I know little about ammunition etc.
Found this casing amongst family military things and can't find any info online.

Can you please help me identify where and when it may have been used?
My father did multiple tours of Vietnam and my grandfather was in WWII.
Could it have belonged to either of them?

Thanks in advance - I'd just like to store it with the correct persons memorabilia.

Not sure how to add a photo. on the end of it is stamped:  303MK7Z  with a PP or PD?-73

Kerry

Sounds like a late production (1973)  .303 inch rifle/MG cartridge case, the standard British (and associated) round from before WW1 to the 1950s.  The Mk 7 indicates a ball loading (which is to say a standard military bullet) the Z means that it was loaded with nitro propellant rather than cordite.  PP could mean Prvi Partizan, a Yugoslavian company which still makes ammo in obsolete military calibres.