...I wouldn't manufacture ammunition for sale even if the law didn't require a license. Ammunition manufacturing exposes you to a great deal of liability (and other issues) and I'm not sure there is enough money in it to justify the hassle.
There are plenty of avenues available to protect yourself and your business, but you do need to ensure that your product is not faulty.
There are two basic approaches becoming a manufacturer:
1. "Go big or go home" - the common choice (your choice) would be going home.
2. Create a business model that is sustainable with small quantities of premium ammunition. - again, the most common choice is to just forget about it, and not even try.
There's no reason to less of anyone that isn't willing to try. It's just that some people are more willing to take the risks involved.