Argo;
Are you referring to the word choke marked on the left barrel flat? I believe this is a part of the re-proofing. Note though the 11 over 1 & the 11 on this flat appear to be of the same configuration as the 11's on the barrel tubes. This leads to some confusion as the between sizes (11/1) did not exist prior to 1887. Could it have been proofed three times?
I believe the reason it was not marked "Not For Ball" at original proof was that it was proofed with 11 gauge bores & no doubt the muzzle was not too small to pass a normal ball as used in an 11 gauge gun. I do not feel the lack of this mark would guarantee it was made prior to the introduction of the mark.
One can push a snug wad through the bore from the breech & if it has a recess (Jug) choke it can be felt. With a recess choke, the wad will suddenly go free while with a normal choke it will become tighter. Either way is easy to feel.
