Gabe

Here's a link to a H&H gunmaking video...

https://www.youtube.com/watch?v=qUXoNUzAyvk

At 09:40, 16:00 and 17:25 you can see some stock finishing going on... wet sanding, grain raising and then the oil finish being applied.

A very truncated version of what goes on but there may be some hints to the knowledgable

You are quite right, the 'new' condition H&H stocks display quite a high gloss finish.