Just received the letter on #27257. The mystery was what the initials "L & K" stand for, as stamped into the wood on the underside of the forend:
The letter states that the gun was shipped to
Liddle and Kaeding in San Francisco on Dec. 14, 1882. L & K were gunmakers and dealers, 1872-1889, at 418 Washington Street, San Francisco. Details on the brief history of what was for a time the largest sporting goods shop in San Francisco can be found online.
Other than that, I am happy to say that the gun is in the original configuration in all respects, although I haven't checked the chokes. The letter lists them as RH and LH full (195 #8 pellets in a 24" circle at 45 yards for both).