The result of your conversion between grain/gallon [UK] and kiloton/cubic mile [US] appears here
To convert between Grain/gallon [UK] and Kiloton/cubic Mile [US] you have to do the following:
First divide ((0.45359237/16)*(192/175)/480)/0.00454609 / ((0.45359237*2000)*1000)/(((0.0037854118/231)*1728*27)*5451776000) = 65.49084477
Then multiply the amount of Grain/gallon [UK] you want to convert to Kiloton/cubic Mile [US], use the chart below to guide you.
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