Romulus. I don't know it hot water will do the trick, but I'll bet Mpro's MP-7 will. (1-800 yes 4mp7) Really good stuff. Clean your guns thoroughly with it in the same manner as you normally would. Then, use a good copper remover like Sweet's 7.62 to remove all copper fouling. Use the MP-7 to remove all the Sweet's and oil the bore well. (MP-7 will remove all oils and solvents. Oiling after MP-7 is a must.) After any shooting session, run a patch soaked with MP-7 through your bore first, then your regular solvent. MP-7 will remove powder residue faster than regular solvents.
No, I don't own any stock in the company. I'm just one hell of a satisfied user.
Paul B.