That's true. They are not very accurate. But, according to my gunsmith, who employs four full time gunsmiths, it's because one needs to remove all the lead buildup in the rifling before using it. Then your rifle, or handgun, should shoot well. Haven't tested this myself, but it does make sense, and I've always found that he knows what he is talking about.
The trouble is that once you clean the gun, you must do so whenever you shoot any lead ammo..... E