Ah, thanks Larry...that's a real historical help for me, And Miller, you guys are fonts of knowledge! I notice that the "Tiger" group who did the original analysis of 19236 commented that it was a nominal 10 bore which actually measured out at 11 bore. I think their analysis is correct - that the H.Walker patent use number puts it at early 1875 and that there were no 'NFB" or original "CHOKE" stamps on it.

Actually on my chart dating Reilly serial numbers, 19236 would have been numbered in early 1875. (The problem comes of course in identifying when exactly Reilly numbered his guns - I'm leaning more towards "date of sale" at this point).
And RAR - sorry to have hi-jacked your line.