I was showing off my Vaquero at the office this morning, and a friend noticed a logo stamped in the side of the revolver. A rampant bull in a circle, and wondered about it. Here's a picture taken from my cell phone.
I went to a computer and started searching for this logo. I came up with something interesting.
That's a pretty good match for the logo. I've got an email in to Turnbull Restoration to see if they know anything about the gun I'm now calling the Mancum Ruger. We'll see what Turnbull can tell me.