Flat-nosed bullets are generally preferred as they cut cleaner holes in targets, have less tendency to ricochet, and wound better than round-nosed bullets. Both 9mm and .45 ACP do have factory loadings available with flat-nosed bullets. The reason that so many 9mm and .45 loadings still have round-nosed bullets is that these two cartridges are much older than .40 S&W and there are many older guns that will not function reliably with flat-nosed bullets.