The Torsion Pendulum

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Gun MOI - Typical Values

The gun in the sample calculation has an MOI of 0.147 slug-ft^2.  Gough Thomas would have reported this as 147 to make the numbers somewhat easier to discuss.  Others have proposed calling this value 1.47. If left in actual units, the values typically range from 0.100 slug-ft^2, or even smaller, for lightweight small bores to over 0.200 slug-ft^2 for heavy target guns and ten gauges. In my experience, the classic English game gun comes in around 0.140 slug-ft^2 to 0.160 slug-ft^2.