So I've never heard of this case before, but after googling it and reading the case summary, it only proves my point.
Pulled directly from the case summary on courtlistener.com:
Absent explicit legislative intent to the contrary,” we give the words of a statute their “plain and ordinary meaning.”
Carbon Fuel Co. v. USX Corp., 100 F.3d 1124, 1133 (4th Cir.1996). The plain and ordinary meaning of the word “manufacture” is “to make into a product suitable for use.” Merriam-Webster Online Dictionary (2010);
see also id. (listing as related words “assemble, build, construct ... refashion, [and] remake”). We therefore conclude that manufacturing firearms under § 923(a) entails assembling a firearm’s individual components so as to render the firearm “suitable for use.”
3 The manner
*676 in which Broughman conducts his gun business;
i.e., “build[ing] custom bolt action rifles” by threading and chambering barrels to fit firearms actions, bluing the actions, and making and fitting stocks to the actions and barrels; undoubtedly places him within the statutory category of a firearms “manufacturer.”
In layman's terms, Broughman was buying bolt action receivers from other companies, and then assembling them into fully functioning rifles by threading barrels, refinishing components, and making stocks,
then transferring the firearm to his customers. ATF (Carver) said that made him qualify as a manufacturer and he therefore needed a manufacturers license, because he was assembling the firearm before transfer.
If Broughman had transferred the bolt action receiver as a receiver, and
then built the rifle out, that would fall under gunsmithing and would not require a manufacturers license, only a dealers license (which covers gunsmithing.)
This is consistent with what I said, that manufacturing happens before transfer, gunsmithing happens after.