To make it simpler and closer, you might want to check with local American Legion, VFW and Amvets posts that might have one on their front lawn. There's actually an open-tripod 20mm (Mark 10) at a post near me. The bad news is that the mounting ring is embedded in concrete. Once someone were to get it free, it could use a good pin-chipping or stripping. It doesn't look particularly well cared for.