I buy Pro Shot or Dewey bronze bristle brushes 6 dozen at a time per caliber, and have since the 80s. Also, use the Iosso and Montana Extreme plastic brushes for scrubbing back and forth to remove the worst of hard-cooked carbon. I had access to a bore scope since 1987, they were the first medical devices.
The very, very best bronze bristle brushes are good for 50 strokes, then use them for tough scrubbing with Bronze wool wound in them with Iosso Paste, Flitz bore cleaner, or JB. This method has been developed by folks that shoot hard. Thurro Clean is a relatively new product that is producing fine results, bore scope says, but I can't say it is much better than Flitz bore cleaner, JB Bore Brite, or Iosso paste. I will warn you that overuse of some of these abrasives can open throat dia, with regular Flitz being the least offender. I measure throat dia with a PTG Grizzley rod and large sets of reamer pilots graduated in 0.0002 increments.
If you consult the Machinist Manual, you will see that the Coefficient of Friction is greater with Plastic on steel vs Bronze on steel.
The very large bristles of the best Plastic brushes do not clean well in the radius of the bore dia and land height.
The tips of the brush are what do the scrubbing aiding by the amount of flex in the bristle putting pressure on the bristle tip. As the brush bristle wears, the force that the bristle exerts diminishes. If you use an oversize brush, you are bending the tip away from the bore surface where the shank of a bristle is contacting the bore, Bristle will break. While the brush goes through the bore very tight, the brush may not clean effectively. Bore scope tells all.
Some new cut rifle barrels are hell on wheels to clean, especially copper. NEVER depend on patches to tell you what is clean.
I hate cleaning gun barrels with a passion, but it has proved absolutely necessary to keep the carbon out of the barrel for those tiny groups that will give me incredible accuracy at 600 yards. Copper is a very minor issue compared to carbon.
I have bought many used Match SS barrels that were not shot out, but they were simply fouled to the point where they had "lost their accuracy". Paying a gunsmith $90 per hour to clean your barrel is not prudent, thus he recommends a new barrel. Said barrel owner had rather replace barrel than clean gun barrels, to each his own, barrels are expendable.
