NOTHING works better than hot, soapy water.
The corrosive element in the ammo is a salt. Nothing will dissolve the salts BUT water. Some people use Windex, thinking the ammonia helps but it does no good since ammonia cannot dissolve the salts.
It's the water in the Windex that works.
The old-time technique is to boil some water in a pot, then squirt in a few drops of liquid soap.
Remove the bolt from the rifle, and stick the muzzle in the pot of hot water.
Put a tight fitting patch on the cleaning rod and run it down the barrel.
When the rod and patch are pulled back out, the suction will draw the hot water up the bore, dissolving and flushing out the salts.
When the barrel is hot, run a dry patch down it and it will dry almost instantly.
Then, clean as usual with brush, patches, and bore solvent to remove the copper and carbon fouling.
Use patches soaked in water to wipe off the bolt head, and the receiver around the chamber, anywhere the corrosive fumes may have come in contact with the metal.