Biggest mistakes people make IMHO is not paying attention to the alloy and not getting whatever alloy they are using hot enough. A good friend of mine showed me how to build my own P.I.D. which basically regulates the temperature you pot operates at within 5 degrees +/-, mine works much closer and works to close standards from initial pour to the bottom of the pot. I do not use scrounged alloy for anything I shoot, I know guys that used to like to dig around after us muzzle loaders were done because they knew our stuff was as close to pure lead as possible. You never know what your dealing with when it comes to scrounged lead and if your barrel starts leading up you know whos to blame. I like dealing with a known quantity like wheel weights, linotype, smelter lead (Bunker Hill), or sheet from roofing or xray room sheathing. The xray room sheathing lead is the best I've found for quality, 85lb rolls nearly 1/8" thick. I got started smelting lead for muzzle loading, got to talking with the cast bullet guys and after getting a come to Jesus talk by one of the old timers that told me "If your not casting your own bullets, your not truly reloading, your just parts replacing."