Not necessarly true. If you shoot muzzleloaders, you want "pure" lead. Or, if you get the pure lead at a bargain price and have harder lead or sources of tin and antimony (already blended), then you can make your lead casting supply last longer. In the years since I have been casting (early sixties), I have never found a supply of lead that was not usable for casting some type (muzzleloader, handgun, rifle), of bullet, all the way from pure lead to the various type metals.It's the 'thud' sound you don't want to hear.