Proof sizes

Relationship between bore/gauge size, proof sizes and calibre of smooth bore arms prior to the 1984—89 Rules of Proof The lines indicate the parameters of the nominal bore/gauge sizes marked to the right of the columns.

Dimensions and parameters of nominal bore/gauge sizes of smoothbore arms under the 1984-89 Rules of Proof

Chamber Lengths

1954 Rules of Proof converted to CIP values

Mathematical conversion factors

Shot loads