Though some of my research some people argue intent. You have x amount of reloaded ammo for your 270. Your intent was to shoot it in your 270 but you decided to see your 270 because of what ever reason. Now you have x amount of 270 rounds with nothing to shoot them. Some people have argued that your intention was not to manufacture the ammo but to shot it. This is the same argument when it comes down to manufacturing home built firearms. You can not manufacture a firearm without a 07ffl with the intention of selling it. But you can manufacture a firearm and decide after it is manufactured that you no longer need or want the firearm and sell it.
So my question is how is ammo any different the a firearm?
There is no difference.
If you build a firearm for your own personal use and get bored with it you can legally sell it.
If you build a firearm to SELL you need to have an FFL.
If you load ammo for your own personal use, and at some point no longer have a use for said ammo, you can legally sell it. It would be no different than if you went to the store and purchased ammo and later sold the gun, you bought it to use, but now don't have a use so you can sell it.
If you load ammo TO SELL, you need an FFL.
Now to really confuse the issue...................
I hold an 01 FFL, I can legally sell you all of the components to build your own gun, then after selling you the components, you could then bring said components to me ( if I were a gunsmith and offered this service... ) and I could then build YOUR components into a working gun and it is gunsmithing, NOT manufacturing.
On the other hand, if I were to buy all of the components and BUILD a gun to offer for sale, I would be in violation as my 01FFL doesn't not allow manufacturing.