I suggest saving your sanding dust until you are completely done. If there are any cracks or gaps or even mistakes you can mix up a filler made with your gun's own sawdust to help blend any repairs. Doesn't help much after you've stained and finished it, but before that it's useful.
What are you doing for the barrel? For the period correct look, I recommend browning the barrel. It's not too hard, doesn't take a lot of materials - just time and elbow grease.
What are you doing for the barrel? For the period correct look, I recommend browning the barrel. It's not too hard, doesn't take a lot of materials - just time and elbow grease.