I don't know of any tutorials. I've done a little work with rawhide, including knife sheaths and so forth covered with thin deerskin rawhide, and various projects from very heavy parfleche. I've never applied it to a gunstock, so can't speak from personal experience.
Generally speaking, I would recommend that you get your rawhide from a leather dealer if you don't make it yourself. Some dealers sell it in smaller pieces, so you shouldn't need to buy a whole hide. I know a lot of people have used and like the "dog chew" rawhide, but I've not been favorably impressed with it. Some of these dog chews have been soaked in brine to enhance the flavor for dogs. Salt is not good for guns.
If I were going to wrap the forestock of a rifle, I would probably apply some sort of wax to that part of the barrel that will be covered by the hide, understanding that the rawhide will essentially make the barrel non-removable. Once the hide is on there and dried, I don't think I would treat it with anything else. Just handling the gun will put some grease and blackpowder soot on the rawhide in time.
This old carbine is a Springfield Model 1866 "Trapdoor" breechloader. We aren't supposed to discuss breechloaders on this forum, but we're looking at the rawhide wrap more than the gun, so I hope the moderators will let this one pass:
I wanted to show this one specifically because the fore-end has a rawhide wrap, and that's the part of the gun the OP was wanting to cover. The other reason to show this gun is because there are some really great detail photos of it. Here is the underside of the rawhide wrap, showing the sinew stitching:
It looks like they just used a simple overcast stitch. There are also some tacks to help secure the wrap. There are more photos of the rifle here:
Tacked Springfield with Rawhide Wrap
Moving on, Luther "Yellowstone" Kelly famously covered the forearm of his rifle with a bullsnake skin:
It's kind of hard to see in the picture above, but in this enlargement you can see the scale pattern on the skin:
This description of Kelly, from
Back-Trailing on the Old Frontiers, mentions the snakeskin cover:
Finally, since the original concern was about the brass "spacer" in the forestock, this is a picture of mountain man Joe Meek's rifle, "Old Sally":
Note the apparent joint in the forestock, just ahead of the entry pipe. I can't say for sure that we are seeing a spacer, but it sure looks like one. Just something to consider.
Best regards,
Notchy Bob