I, just last weekend, went to clean my rifle after 100 rounds of working it. Usually when I clean this target rifle I remove the brake as the brake really loads up with copper and carbon from use. No big deal. The barrel is easy to clean and doesn't indicate much copper and I assume this is due to the fact that it is a Krieger hand lapped barrel. What I found this time when I removed the brake when cleaning the rifle is that the crown had massive carbon deposti build up on it. This stluff was as hard as steel and required massive scrubbing with a stiff plastic brush and soaking with Hopps solvent to remove it. Actually I just went after the crown of the barrel today after soaking it for 2 days in Hopps solvent and the final chunks of carbon came off. I do sill have some scaling left on the crown whare the carbon chunks came off and am soaking for another day or two before I attack this ramaining carbon deposts. This carbon build up on the crown is new to me but I have been told that it is common when using a muzzel brake and that there are cleaners used for just this purpose. Soaking for a coupel of days or so worked for me and I imagine the scaling will come off after soaking for another day or two. I'm just passing this along for those that have muzzel brakes and that may have accuracy issues after a short while of shooting with these things. As you may or may not know crowns must have no build up or even micro scratches on them if you want good accuracy.