Question for you artillery / shooting folks.
I am contemplating a large scale scratch build of a US Civil war 3” Ordnance rifle .
IIRC the bore diameter is taken between the lands
( minor diameter) as opposed to between the grooves ( major diameter) .
Do I remember correctly ?
Thanks in advance for any help .
Cheers - Richard
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That is how we currently measure it. Old Soviet bloc/Russian howitzers measure it in the depths of the grooves. If your model is going to be so precise, that it takes those lands in grooves into account, that’s going to be one hell of a model!
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LOL - yes it would ! I think I needed to satisfy my own curiosity as much as anything. I’ve been musing about ways to produce the rifling .
I watched the gunsmith at Colonial Williamsburg cut the grooves in a Pennsylvania rifle some years ago and will attempt that method if I do this . I’ve ordered a book of plans for Civil War guns / carriages that are from the actual government drawings. Thanks for the help .
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The basis of measurement was not consistent between countries, services, or over time.
Remember also that it was not until after WWI that the US adopted dimensional standards based on a dimensions rather than gages. So, for example, while all the 3-inch rifles made during the Civil War were the same size regardless of the arsenal that made them, that size may have been 3.064 inches.
KL
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Thanks Kurt - all very interesting. It will be interesting to see how the barrel is dimensioned on the drawings when they arrive.
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Do you know anyone who lives near Gettysburg PA? There are several 3" Ordenance Rifles on a hill as you approach the town on the Chambersburg Pike. (some were used in the battle in 1863). Someone with a pair of calipers could answer your question very quickly.
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Thanks - I am not too far from there and plan on making a visit if I go through with this.
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