Interesting stuff MM.
When you say "found", do you mean in/on the ground or at auctions etc?
Is that the tail end of a mortar there? I once saw a shaped bit of metal sticking out of a bank in an old quarry. After a few good kicks it dropped out and was the tail end of a, fortunately already exploded, mortar shell. On getting home and goggling the site I found out that the quarry was used as a firing range during ww2. Local rumour has it that there is a fortune in spent brass cartridge cases dumped in the vicinity.