kwhi43, there does appear to be more markings than just the PN you mentioned on your cylinder. In your 4th picture of your first post, (the pic of the bottom of the revolver where you can see the serial number), look just above the serial number and there appears to be an "A" marking. Not sure what significance that has, but it is a marking that doesn't appear to be part of the serial number. ASM? (Armi San Marcos?), ASP? (Armi San Palo?)
I tried increasing the contrast in photoshop to give a better view of that "A" and you can see that in my attachment link, along with an arrow pointing to it.
I can tell by the screw holes of the frame being dished out on their edges, that the frame has been heavily buffed at some time. The screws aren't buffed to match the screw holes, so obviously the screws were removed before it was heavily buffed, hence the dished out edges of the screw holes from heavy buffing. So it may indeed have been "defarbed" as someone else suggested. But again, check out that "A" marking above the serial number I mentioned and showed in my attachment, it may be a clue.
Also, have you checked for markings under the loading lever?
Also, check out my second attachment. I also decreased the brightness and increased the contrast to try and see what those two buffed out markings are on the right side of your frame. Check them with a magnifying glass and try to get the light just right so you can see any vestige of detail that might be left there in spite of the heavy buffing. They are heavily buffed out and pretty much destroyed, but under the mag glass with the lighting right, you might maybe get a clue. Something about that forward most mark, brings to mind a CVA (Connecticut Valley Arms) marking, but that's just a gut feel guess on my part. On the most forward positioned mark, it's very hard to make out and even looks a bit like a mushroom cloud who's "stem" of the "cloud" looks slightly to the left of the upper "cloud" instead of the "stem" being centered directly under the "cloud". Of course both of them could also just be heavy dings and I'm reading too much into the forward most marking.
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