I have a probably stupid question but I need to ask. I acquired a William Powell & Sons best quality Hammergun manufactured in 1873 and was wondering what the function of the holes in the top of the action as well as the screws on the side. They appear to be gas port holes? I am sure one of you very knowledgeable members has the answer. Also do I need to clean them in some way? See attached.

Thank you in advance.

[img]https://imgur.com/a/Xn4Yhdd[/img]

Steve