I have a small hairline crack maybe 1/2" long on the tip of a forearm of a stock I'm refinishing. It's a tight crack and is not gapped. I intend to oil finish and am not sure if you can sand an oil finish like you can Pilkington gunstock finish. If I used Pilkington it would be a piece of cake. The initial wet sanding would blend it in fine. A straight forward hand oil finish will not hide it. Any suggestions??

Wet sand it, creating a "mud" coat. Rub it into the crack and let it dry for a week. Then wet sand again back to the surface and it should be filled. Using oil will be fine.