Here is a 20mm shell casings retrieved from "The Bulge". This is what I am told. A person I work with lost her husband to a heart attack and she has been clearing things that she does not want and came across three 20mm shell casings. She told me her husband knew a teacher in Belgium who did some digging now and then and came across these shells. I have no reason to doubt her story but there it is.
Anway, I have no idea what weapon fired these types of shells during that period (anti-aircraft?) so any information you might have would be applauded and stored away in my brain. Thanks and prost!
Also-I have my dinner next to a shell for size reference.