Instructions to Young Sportsmen in All that Relates to Guns and Shooting, P. Hawker, 1846
pg. 47 “Let your barrels be first washed perfectly clean with cold, and then fill each of them with hot water; which by the time it has nearly run out at the touchhole, will accelerate their being wiped dry, as much as though boiling water had been used; and before they have completely discharged the water; stop the muzzles and touchholes; and after shaking it up and down in the barrels, turn it out at the muzzles, by which means you will effectually stir up and expel any extraneous matter that may have lodged in the bottom of the chambers.
“I have recommended washing guns with cold water, from having found that it always more readily removes the foulness occasioned by the powder, which, from sudden heat, is apt, at first, to dray and adhere more closely to the caliber: whereas with cold water, it remains in a moist state, and immediately mixes.”
Spence