Now, for the trickier question: Does the modified barrel, now fabricated from both a foreign made part and a U.S. made part, and "finished" here in the US, become a U.S. made part for the purposes of 922(r)? I believe it would.
I believe it would also because, in the case of the C93 Sporter, the gun came with a tag that says the barrel is made in the USA. Also, the barrel is just over 16" so there would be no need to permanently attach the flash hider to avoid being a SBR, yet the flash hider is permanently attached.
At first I could not figure out why.
These guns are built from parts kits made from chopped up Malaysian Army rifles that were made in Germany by HK, so Century had to be mindful of the foreign parts count in assembling these rifles. Rather than make US made flash hiders, it is cheaper to just permanently attach the German one to the USA made barrel and then the flash hider no longer counts as a foreign part under 922(r).
This issue came up in the first place because I want to install the Slovak made muzzle break, used by the Czech Army and sold by Czechpoint.com, on my SA vz 58 and was wondering how that would affect parts count as the barrel on the D-Technik SA vz 58 is Czech and therefore a foreign part. To the best of my understanding, under 922(r), if you permanently attach the foreign muzzle device, it and the barrel count as one imported part, not two
However, I don't believe the opposite is true in that permanently attaching a US made muzzle device to a imported barrel makes the barrel a domestic part.