The result of your conversion between foot pound and grain/gallon [US] appears here
To convert between Foot Pound and Grain/gallon [US] you have to do the following:
First divide 1.3558179 / ((0.45359237/16)*(192/175)/480)/0.0037854118 = 79.20394151
Then multiply the amount of Foot Pound you want to convert to Grain/gallon [US], use the chart below to guide you.
Symbol: ft lb
No description
Symbol: gr/gal
No description