There are many different ways to cut the barrel channel.
Here is a few links to posts made on our forum about a few:
CUTTING A BARREL CHANNEL
ANOTHER ONE
These deal with using a router with a fence attachment to keep it aligned with the side of the wood blank but some have done the job with just a chisel.
The key is to keep the chisel razor blade sharp and to devise a way to keep the cut straight.
Building a gunstock is not an easy task but if you do make one and it comes out right you will be so proud of yourself you might proclaim a holiday.
Getting a good piece of wood is the first challenge and if you have $30 plus postage you can get a blank from Pecatonica River (an excellent place to do business).
STOCK BLANKS
If you want to get a pre-formed half stock with just the barrel channel and ramrod hole drilled you will have to spend $60.00 plus postage.
Here's a link to those pre-formed stocks.
PRE-FORMED WITH BARREL CHANNEL CUT
For what your doing, I would suggest the Leman Half Stock you'll see in this link
LEMAN HALF STOCK PRE FORMED
I choose the least expensive blank in the simple half stock to keep the prices low. After all, it would be somewhat foolish to spend a lot of money on a stock and then put in some parts that are not of top quality.
If you choose to do it this way, call Dick Greensides at (815) 968-1995 and tell him what your doing and make sure he understands that you do NOT want the lock mortice or the trigger mortice cut.
This will allow you to fit your lock, trigger, trigger guard etc so the mortices match your hardware.
The way I figure it you can have a nice stock for your hardware for about $75 and save yourself the headaches of trying to cut a barrel channel and drill a VERY deep ramrod hole.