Looks like Gun Barrelmakers Company from 1813, which covered all of England and Whales. The crossed scepters where used by a gunmaker of Ketland and selected as the proof marks. the left side of the cross is a B, the right side a C, and the bottom of the cross a P. It was also used by the Gunmakers Company proof facility in Goodmans Field, Whitechapel,London where it still stands. The barrels could have been made in England and sent to Germany. These are the only Proofs i have seen that has any resemblence.
