I've also heard of 1918 LSAs with the cut off and windage sight, I can only assume that perhaps LSA changed to Non volley sighted wood in 1916 then. I also have a BSA dated 1917 Mk3 with the cut off slot yet I've seen a 1916 BSA Mk3* with no slot. They must of had hundreds of bodies sat in various stages of the manufacturing process awaiting the next machine.