U.S. Smooth bore musket bore diameter variation?

[haddockkl]

Does anyone know off the top of their heads what the allowable variation was in bore diameter for U.S. service muskets? I'm curious what the largest allowable bore diameter might have been or that's been observed on original, unmolested examples.

[Don Dixon]

This will give you an idea of what was in the field and the armories, and what the Army considered acceptable for continued use. In 1842 the production of all flintlock muskets for the Federal government was halted. When the decision was made that same year to transform flintlock muskets to percussion using the cone-in-barrel technique, the Army had to determine how many flintlocks it had in inventory and which weapons were suitable for transformation. Lieutenant Peter V. Hagner was appointed to supervise the inspection and classification. Over the next six years Hanger found that 700,000 flintlock muskets were in inventory. As a first cut, all muskets manufactured prior to 1812 were condemned, as were all muskets manufactured after 1812 which were not deemed worth repairing and transforming. All "good and serviceable" muskets manufactured after 1831 were characterized as first-class arms and were not further inspected. Hagner's three inspectors -Elizur Bates from Springfield Armory and Philip Hoffman and later James P. Chapman from Harper'Ferry Armory - were given three gauges to inspect the muskets manufactured between 1812 and 1831. The first was a tapered plug gauge used to measure the musket's bore diameter at the muzzle. The second and third gauges were .690 and .705 inches, respectively. If a musket's bore gauged between .690 and .695 inches it was characterized as second-class. If it gauged between .695 inches and .704 inches, it was characterized as third-class. If it gauged more than .705 inches it was characterized as fourth-class and condemned. Condemned weapons were set aside at the arsenals for disposal, third-class weapons were deemed unsuitable for transformation and were kept in storage essentially as a war reserve, while first and second-class weapons were considered suitable for transformation. Colonel Craig, the Chief of Odnance, wrote on 1 October 1854 that of the 707,011 flintlock muskets inspected 337,092 were assigned to the third and fourth classes. Regarding the quality of all the Army's smoothbore muskets, Craig stated that the inspection "show[s] at a glance the very large proportion of the arms that in point of quality fall below the proper standard, and when explained to the [Ordnance] Board that the inspection was made by two workmen from the armories who had been employed there at the time these arms were fabricated I can not [sic] but think it will satisfy them that great carelessness must have existed at that time in the armories."

Regards,
Don Dixon

[haddockkl]

Thanks Don, that is very helpful.... and interesting

[Dave Fox]

Thanks for this explanation, friend Dixon. Information I didn't have. I may well be missing it, but don't see the specification for bore diameter of 1st Class stored .69s.

[Don Dixon]

.690. You can't issue weapons with under sized bores, because once the windage gets sucked up by fouling in the bore bullets get hung up in the bore, effectively disabling the weapon.