I purchased a CZ 452 for competition second hand and took it home to clean it. The barrel would only let my jag/brush get halfway down the barrel. Is the barrel extra tight? Leaded up? Should I just leave it alone and keep shooting it? Good product to remove lead in Rimfires? Excuse my questions, I am new to the rimfire game and only used them to shoot rabbits and squirrels before. Most experience is in centerfire benchrest.