Although I am quite familiar with modern firearms and ammunition, I am far away from an expert on all ammunition and especially old stuff.
I found this fragment of canvas belt-fed ammo in cleaning out an estate. I was led to believe that it probably is from about the WWI era. Other than that, I don’t know what it is or what weapon it is for.
The stamp on the rim is WRA and the number 45, but it’s clearly not a .45 - it’s more like 9 mm.