Friend has an abolt 2 in 7rem mag. and has fired it only 5 times. I got some dyna bore coat and he wanted me to apply it to his rifle. I took it home and cannot get it clean. I've cleaned on it for a couple days. Hoppes till patches started coming out clean and have soake it multiple times with patch out and then scrubbed with a brass brush. When I thought I had it close to clean I used bore paste then wiped clean with hoppes. Started the patch out again and it's completely nasty black patches after letting it soak for a couple hours. I have noticed throughout this process that after about ten inches down from the chamber the barrel gets real tight when I'm running patches down it. It takes twice the pressure to push the patch down the barrel once I get to this tight spot then after a couple inches it seems to loosen back up. I take it I just have a right spot in my bore. If so what's going on here? It should not be that hard to clean after 5 rounds should it. What can I do to fix this