Hello I have a couple of bolt actions that are seeming to be clean but when I look with the bore cam I am seeing a smooth black coat. I actually am seeing this in 2 right now, both are Remingtons, one is a model 710 .270 and the other a .300 rum in model CDL. I have done a multi stage cleaning process using all bore tech cleaners, jags, patches, nylon brushes etc.. I thought maybe at first I had let something dry but they advertise all of the products able to sit and I haven’t been mixing or anything like that, just one at a time. Non of the multiple others have this black coating that will not budge like these 2. Wondering if it is a heat/season type deal or if something had been done previously that made this coating? Not sure it doesn’t seem to be carbon and can’t imagine it could be from any products or anything I did.