I use plane old cold water a patch pump it several times to flush the niple clean repeat with nylon brush then fresh water and pump with a couple more patches till clean,I do use a vice with a thick peice of leather to hold the barrelthen dry and oil. Hot water promotes a flash rust but I do clean with super hot water once in a while to get the seasoning out and start over again when my 3 shot 1 hole group starts to expand. The whole prosess takes about 15 min from start to finish.
O Mlinkrpt put some of that dishwasher soap in your hand add a bit of water rub your hands together the heat you feel isthe acid they put in the soap that eats up food grinders