pretty sure its an error by proof house stamping. Burrard gives 7/8oz load for all 3 lengths at provisional proof but shows 1oz for 2&3/4 & 3" @ definitive proof. My copy of 1954 Rules of Proof show Definitive load of 157 grns TSP & 1&1/2 oz No6 Shot as the Definitive Proof Load


Hugh Lomas,
H.G.Lomas Gunmakers Inc.
920 876 3745