Sabotloader - lead oxidation occurs pretty quickly. If your conicals are new and shiny, take a pen knife and shave a flake from the conical. Note the color differential side to side. How does it compare to the "lead flakes" coming from the barrel? If the flakes are old, one side may be dull, the other shiny. I'd guess the flakes are from the shot you are taking now. Also, the constriction you note at muzzle and near seating are likely from different causes. There is probably very little lead near the seat, more likely pitting from having been left uncleaned at some time in its life. Shouldn't have much impact on performance but difficult to make smooth. The muzzle end sounds like fouling as you shoot. Was it easy to load the first couple of conicals before you became aware of it? One thing I think may be important to keep in mind. You and I and others who frequent this site, in terms of the frequency with which we shoot, are exceptions to the rule. If that barrel was "used", it was likely used very little, suggesting the things you're encountering are more likely the result of neglect than overuse. It's obvious from your targets the barrel will perform. But could you get that truck washed! Geez...