I am using CCI primers. I talked to Thompson Center customer service and they told me I can do the JB Bore Paste, or shoot a box of lead bullets through it. If that does not work they want the barrel back. I am no expert, but I don't think this will fix it. The bore is so tight that the ramrod paint is coming off due to it bending so much while going down the bore. I can't even get a powerbelt down very well.