1909 King’s Military Regulations, Part 1, paragraph 101
“An effective means of cleaning the bore whether firing has taken place or not, is found in the use of boiling water. Before boiling water is used superficial fouling and grease should be removed. About five or six pints should be poured through the bore from the breech, using a funnel to prevent its entering the body or magazine. The rifle should then be throughly dried and bore oiled. Not only does the boiling water remove the fouling, but the expansion of the metal due to heat of the water loosens any rust there maybe and makes it easily removable.”
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