lazs2, chasing cast rounds with jacketed is a bad idea. it will cause sever leading of your barrel. if you fire alot of cast rounds then you know if you load them too hot the speed causes enough friction to bond the lead to the barrel (kinda solders it on) firing jacketed rounds (at much higher speeds) after fireing casts makes the barrel look cleaner, but in the end it has the same effect, just a 2 stage process.
if you fire cast rounds you should get a good bore solvent and a brass or copper brush.
btw they make a electrolisis (sp?) tool that electricly removes built up lead but I've never tried it so don't know how well it works.