I got out my three bolt action .30-06 Milsurps to get ready to develop cast loads for them. I have had them for awhile and decided to give the barrels a good cleaning. I used Patch Out and got lots of blue patches. I kept at it until the 03 and the 1917 Enfield were coming out pretty clean. The third, a Columbian Madsen, is still leaving patches blue. I admit I had never cleaned them with an ammonia cleaner until now. I am somewhat surprised that the Madsen is still showing copper fouling after many patches and brushings.
Should I continue until I get a clean patch? Any advice will be appreciated.
Edit! I'm brushing with a nylon brush. The blue is not from a brass brush.