Herein lies your challenge and strategy.
The big manufacturers would likely not wish to purchase your product as ingredients, they would most likely wish to make it themselves under licensing agreements, to control QA and economies of scale, many/most will already have in-house production.
However, you will also find that paying you royalties (if just using your recipe), will be unappetising for them, and so they will firstly do everything they can to legally ‘copy’ / reverse engineer your product, or come up with their own close performing one (after all, it’s a matter of trial and error in the mixing bowl, and any small change from your recipe avoids patent infringements).
Big companies will want an exclusivity arrangement, so if you found a partner, make it count for both pellets, bullets, etc and esp a player that covers the US market, but they’d likely copy and dump you, and get away with it.
Personally, I’d target small niche and strategic ammo manufacturers who do not have the skills to reverse engineering, and who do not produce pellets in-house.
instead of taking the risk of being copied and thrown by the wayside, you would have a niche.
Maybe purchase production assets from George Young and manufacture cartridges in-house?