it sounds like a dirty barrel.i seen this on range with round balls.i saw people break their rods trying to pound ball home. try soaking barrel in your favorite cleaner.let it sit and loosen up inside, then brush and hot water.i use car brake cleaner in spray canto really clean my barrel ,it works great.it comes with a plastic straw so you can spray into breech area and down barrel.its cheap to at wal-mart.