psuklinger,
The insert and triggerguard are made of horn( buffalo) rather than bone.BTW,it was not mentioned that the 16 ga chambers are 65mm (2 1/2-2 9/16")instead of 70mm(2 3/4") which is the current standard.It may have been rechambered and not marked, so checking it would be worthwhile.With the new photos, I now see the 233.While it is not in the usual location, I still believe it is the proof date.The extensions Raimey pointed out as being rare are basically the reverse of "side clips", which were peened in from the reciever and I believe easier than the extensions.It would be interesting to know how the extensions were added.The stock seems to have been refinished with the addition of a recoil pad.Others may criticize this,but in my opinion, there is nothing wrong with it.Now that I see there is a scope included,you have a very fine and useful drilling.Use it often and enjoy it.
Mike