I visited the ATF site to get a reference, but couldn't wade thru the complex cross-referencing. I do not believe an FFL is needed just to make bullets, but state laws concerning working with lead, having a manufacturing and retailing business, and the federal 10% 'sporting tax' make things difficult. I'm sure there's more than a few businesmen on this forum that can help you with specifics, but for legal questions I'd spend time reviewing the ATF regulation, and your state firearms regulations themselves.
Later: I took a look at Tital 27, US Code, section 178.11 and 178.41. The law defines bullets as Ammunition, and manufacture of ammunition for sale requires a $10 annual licence (Class IV FFL??) The exceptions are armor percing, explosive, and antique arms bullets. The biggie about that licence is not the cost but the background check.
