A small diameter barrel with a low serial number of “51” also stamped. Tapered barrel with a single ring near the bow. Fine pocket wear. A nice bit from a hard to find Texas railroad with a long history going back to the pre Civil War era.

A fellow collector sent what follows in italics. Please remember that NOBODY knows EVERYTHING:

Key #20, the GH&H key. Texas keys are my forty year passion and I have only seen two or three each of the GH&H switch or car keys either in hand or in scans or drawings. The two bits are consistently the same the few times they have appeared as this bit doesn't remotely match either. That in itself would not be troubling, this is definitely an old key but the marking is not, and is not consistent with markings from the era of the key. I would bid heavily on this if I thought it legit as it would be a variant from the two keys I have but the marking is jarring to look at, it isn't really of the era of the key. I was hesitant to say anything as this type of info is seldom welcome but figured I'd point it out early for you to use as you see fit. Others may have an entirely different take on it and no one elected me the key police.

Excellent