Probably US. Driggs was an American co. late 1800s to early 1900s. Was gobbled up in a merger .
I was thinking projectile for the 3" 15 pounder M1903 Seacoast gun....
The threaded hole opens up into an interior cavity.To clarify, does the threaded hole in the base open up to an interior cavity for a filler, or is it just a tracer hole?