Hinge Pin not Engraved/Finished

[Jeffrey H. Smith]

Having viewed many pictures of Parkers in the past couple years now, I'm wondering the significance of my gun's unengraved hinge pin. This 10 ga. lifter was built jn 1874, considered a $105 dollar grade gun I am told. It has also been suggested this gun has a little "extra" engraving for its grade.
So why wasn't the hinge pin pivot engraved or finished up better? I really don't think I've seen others where this has been left unfinished. Is this due to a "cobblers" replacement? In later years it seems the unique character of the hinge pin attributes was a signature aspect of Parker details. One can identify a later vintage Parker right away by the recessed hinge pin and engraving usually associated with it. So again I wonder why this gun seems left unfinished. Please offer any explanations any of you might have.
Additionally, there is another set pin that I'm unsure the name of that is right between the two hammers and bolsters on the top of the breech at the beginning of the sighting plane. There is engraving nearby this pin, but none to "cover" or blend it into the finish of the gun. Perhaps all the engraving was done before assembly and then these two pins get finished after assembly? But in the case of my gun for whatever reason neither were finished up by the engraver after assembly?
Please provide any thoughts or explanations for this, thank you.
Oh, and please tell me the proper name of that pin between the hammers.

And... in the one pic you can see the hammer faces, and tell the extent of use of each hammer/barrel. I have no idea what to speculate here but some of you may be able to quantify the amount of use each of these barrels have seen based on the strike wear. Please share any thoughts any of you might have here as well.
Some of you might recognize this gun as I've posted regarding it in the past couple years on various aspects of it. I'm just trying to learn as much as I can about my gun. Though it's been in my family over 40yrs, there is very little I know of the gun's prior history. My late Grandmother was an antiquer and came across it and bought if for my late father sometime in the late 60's early 70's about all I know. I have a stock letter on it but no order letter available.