Are you referring to the barrel channel?  There was a thread recently about some shop made cutters for making an octagonal channel.  I did one with a straight end mill in my small Grizzly mill to cut the top and bottom flats followed by a 45 degree router bit. Mostly trial and error. Lots of sanding using an old barrel with different grits attached.   I have used a 1” router bit for round barrels.  For a flat spring channel a 1/2” end mill works.  I am not a good wood worker so hopefully others will share how it should be done. 

Jack

I do this mostly like Jack.  For a tapered octagon forearm done in the mill, I find the center of where I want the barrel.  Using an appropriate end mill I open up the channel so the front will drop over the barrel when positioned around 1 1/2 inches in front of its finished position on the barrel.  I use a depth of 60% or more of the side flat.  I then open up to the width of the bottom flat keeping it centered.  Then using the 45 router bit clean up the angled flat by simply match to the side and bottom flat corners.  Set the roughed out forearm on the barrel with the front down and work the back down until the wood bottom flat contacts the barrel bottom flat.  Then work the entire forearm back to the action and fit it to the action face.  I do the same with a round barrel but just use a router bit to rough the channel out so the front fits the barrel.

Some ask why I inlet the wood forward of the action and then work it back. Why not just straight down at the action?  By working it back I can usually correct any gaps or inconsistencies in my inlet by taking advantage of the taper.  This is especially helpful along the top edge. Leaving the woof an inch or so long is also beneficial in the final fitting.

The last thing I do is lower the top of the forearm to half or less of the barrel side flat, giving me the profile I’m looking for.

This can be done with a router or on a router table.  I’ve done it but it’s lots easier in a mill.

I’ve also inlet a 44 inch swamped barrel by hand, so doing this by hand is also possible and not really that hard, just takes time.
Bob

All very informative, but I think the OP is asking about the ebony inlay in the forend tip.

sorry and thank you for the replies. 

Quote:


I was how ever asking about the ebony insert in the tip of the forend. 

for my barrel channel I wrote a simple program for a cnc machine. used a 1/2 flat end mill to do the bottom of the channel and both sides cutting half the barrel taper for each side and the bottom. then went back with a 45 degree tapered end mill to do the angled flats on either side of the bottom. spent an hour writing the program and three minutes to cut the channel.

The slot for the ebony insert is a dovetail. I can’t recall but I think I used an 11 degree cutter and made two cuts, each cut angled to the centerline of the forend. I’m making a steel insert from mine right now. Check out my .22 target rifle build (You need to Login or Register to view media files and links)
Cheers Richard u

I've only done the inlay once and I used a small drill bit to do the end of the vee shape, and then my jeweler's saw to cut the rest of the vee. Then just chisels to gradually remove the wood inside the vee, and files to get the final fitting.

Chisels gouges and files.