I received the replacement barrel two days ago. I would have posted an update with pictures earlier, but when I had finally gotten around to downloading the pictures, I discovered that someone had been putting finger smudges on the lens again.
So, here's the rundown, currently without pictures.
The actual turned metal barrel that comes with the Voyager set seems decent. The details look like they could have been crisper, and it seems too light compared to the Trumpeter barrel, but it's okay.
The star of the show is the brass muzzle. Absolutely superb! It's just two pieces, and it looks great. I'll be fitting it to the Trumpeter barrel I think, since the connecting peg on the Voyager barrel isn't actually a good fit for the muzzle, and it looks like someone did a really bad job with the metal lathe, as it's really rough around the connecting peg. It takes a lot of force to jam the muzzle into place, and even then it's not quite flush.
This must have been an early product from when Voyager was a new company, because otherwise I can't explain the quality issues. Still, the muzzle is great, and that's all I care about.