Your gun seems to predate most proof houses. Some countries started proofing guns earlier than others. Some countries started proofing earlier to keep cheaper, weaker guns out so their makers did not have to compete. It was always cloaked as a safety measure, and it was. But while British guns were proofed in the early 1800's other countries might not start until 1890's. Some makers had their own marks as well as interim proof marks.