When I was working on guns one of the biggest problems that was common was the wear near the crown from ramrods. There is only two solutions for this problem once you have it [it is very hard on accuracy] you can get a new barrel or cut 2 inches off the barrel and re-crown it.
The fiberglass is the worst one to have, the aluminium and the wood are bad to they pick up grit and grind it against the barrel. Sabotloader is right if you shoot much at all you should have a Crown protector or what ever it is call where you live. They are usually either brass or a very good plastic and are held on the muzzle to keep the ramrod from wearing the barrel out of round. A shooter that only shoots for sighting and hunting will probably not have this problem but those of us that shoot a couple times a week could develop it in a year or two. I have seen a lot of rifle people brought in and could not understand why they lost accuracy that had this problem many were traded in and had to be repaired before resale. Lee