If this is a Lyman Deerstalker, and a slight scratch... if you have some oil and rub it on the scratch they often disappear. A scratch is one thing, a real deep scratch is another. As for the nick in the barrel, that kind of bothers me. Although mine get all chewed up at the top of the muzzle. Like said, the choice is yours whether to send it back or not.

That is a hooked breech system rifle. Or button breech what ever they are putting on them. Put the hammer on half ****, then the barrel kind of slides into the tang, goes under the lip, and then you can fold it down into the stock. It is then held there by the wedge pin that you side through the escutcheon plate.