Stu, that actually is explainable and could be legit. You see how the grommets are brass? The grommets should be steel for an M15 manufactured as an M15. However, brass grommets indicate that this was probably an M1895 with brass fittings that was re-worked by a Instandsetzungsamt (repair depot), a new M15 steel plate placed on by drilling new holes, and then issued again.