As always Steven is correct: "The loads for caliber .454-.299 inches(7.62mm), however, are not designated in the usual millimeter system used for rifled bores, but with the designation customarily employed for marking smoothbored barrels, that is caliber 51.05 - 172.28. The designation here is borrowed from the old British method of indicating the number of lead balls fitting the bore which can be cast from one pound of lead." - Gerhard Wirnsberger
And also from the same: "For calibers not listed in the proof table, the person submitting a gun for proof must furnish load data in writing, as well as suitable cartridges, free of charge, to the proof master."
In 1676 Essen was using the gauge mark for plug gauge diameter, so I would think the trade had plug gauges below 172,28 but wouldn't think the trade to stamp the gauge on the tube for the proofhouse in the preliminary stage but rather the proofhouse to have plug gauges smaller than 172,28 but not load data, which would determine the threefold powder charge and double shot charge weight for the 1st proof, or cartridges.
Kind Regards,
Raimey
rse
Last edited by ellenbr; 12/18/08 11:14 AM.
