Second one of the morning! Has anyone here seen nonstandard proof marks from one of the British proof houses before? I'm thinking, for instance, of a chamber, throat, or barrel which deviates from the CIP specification. If you seen them, what do they look like? For instance, would an American 7.62 x 39 barrel be marked up as: 7.62 x 39 mm (.308") or 7.62 x 39 mm (.300"-.308") Or what? I vaguely remember seeing nonstandard 7.62 NATO proof marks on target rifle barrels years and years ago, but I can't quite remember what they looked like.