no,when your shooting lead bullets, using a larger diameter bullets not only helps keep the lead from transferring to the barrel, but also help with accuracy a lot. you generally try to shoot the largest diameter bullet that you can reliably chamber, well, to a point. if your curious about casting and reloading, hop over to the reloading and casting section and read about slugging your barrels and the benefits of oversize bullets. some guns like big diameter bullets and some guns don't, its about tailoring bullets to a specific gun to find out what it shoots best. a lot of 9's do well with .357. ALL lead bullets are at least .356 for lead instead of .355, just like a .357 takes .358 lead even from the factory.