Yes.. .their investment casting and metalurgy is what makes their metal different.
The first series of Vaqueros and the early New Vaqueros had the finish you are looking for. Early New Vaquero CCH 45 Colt : Cowboy Action Shooting at GunBroker.com
I keep silica gel packets in close proximity to all my guns to help keep any moisture issues at bay.
I use only American Pioneer Powder in my loads as all my shooting is SASS related.
I had owned a 4 5/8" pair of bisley vaqueros originally and one of them developed a big rust spot on the side of the frame just sitting in my case.
I'm pretty a-retentive about how my guns look... with a little work and a cold blue pen, I was able to touch it up and make it look good again; but was initially surprised at the lack of durability in the finish.
True bone case color finishes will wear and fade over time too.
Turnbull offers to put a clear coat finish on theirs.
I agree with you Waveform... they are cooler looking with that 1800's era looking finish.
I just wanted to give you the heads up about the issues that come with that finish.
I keep my guns wiped down regularly with an oily rag system that my grandad taught me when I was a kid.
Now that I am using a BP sub all the time I have modified that recipe to work for me. For smokless powder guns:
take an old flannel shirt and cut out a 12" -16" square out of the back of the shirt or use a bandana
in an old sauce pan slowly warm a few tablespoons of vaseline over the stove to liquefy it
place the piece of flannel into the liquefied vaseline and let it soak it all up
let it cool and store it in an enclosed container (I use the old vaseline container) For BP guns:
follow all the steps outlined above; but use TC Bore Butter instead.
In time, those rags will need to be rejuvinated and can be done so by following the same process over again, just using less vaseline or bore butter