I am sorry but it seems you might be missing what is actually being asked for here. It is not about scrapping ammo into it's components. We had that before and yes it was OP to be able to do. But does not mean scrapping could not yield more than one kind of item, neither would getting more than one kind of item from a crafting recipe. Most items are not made from just one material, a scrapped bullet could yield 1 lead and 1 brass for example, instead of either lead or brass (as it is now).
I agree that when scrapping is concerned it should not ever give back something that can be used in crafting the same thing back again. It should just yield base materials that need to be processed again or turned into more usable materials first and give back less than it would cost totally.
But I get, and probably are right, that you do not want to invest time in a feature that will be mostly be utilized by modders. Just one question though, you spoke earlier of a new feature to unpack an item to get stacks of things, does this allow multiple items to be granted (so 1 of itemA and one of itemB)? If so this could probably be used for the same purpose.