Tips & Tools with Fred Stutzenberger – Part 7
Tips & Tools #7. Inletting the Barrel.
Some wag once said “A muzzleloading rifle is a barrel with some parts attached.” That’s like saying an automobile is an engine with some metal bolted to it. No matter what the analogy, inletting a barrel into a fullstock is a long and exacting task. George Suiter up at Colonial Williamsburg told me that some evidence indicates that the old-timers screwed down flexible pieces of metal alongside the barrel to provide rails to guide a saw for cutting the sides of the barrel channel. Once the sides of the channel were cut, the bottom was removed casually with gouges rather than closely fitting the bottom barrel flats.
I modernized that system by moving the rails (2 x 2 x ¼ x 60” angle iron) to the outside of the blank and using one of them as a precise track for a ½ HP router with an edge guide (Fig.1). The track rail must mate against the side of the stock that is planed very straight. Worked great for straight-sided barrels; for tapered or swamped barrels, I installed an auxiliary set of edge guides on the track rail that I could move in or out slightly to cut any channel configuration I wanted. I always cut just very slightly undersized whether cutting straight, tapered or swamped. My first few barrels were inlet without any cast-off (the extent to which the buttstock is angled to the left [cast-on] or right [cast-off] relative to the longitudinal axis of the barrel), but I soon got to liking a bit of cast-off (no more than a quarter inch). The best way to determine the effect cast will have in your particular rifle is to handle a few with varying degrees of cast. Most of the old rifles for right-handed shooters had a bit of cast-off.
After I got used to using this fixture, I wasn’t satisfied with using that cumbersome combination of straight-sided bits, so I custom-ground a full set of router bits to half octagon shapes (Fig.2). The rounded or triangular cutters were used to inlet octagon-to-round barrels or shaping the fore end respectively. The straight-sided bits at the top were used to remove most of the wood from the tang inlet.
Such an investment of time and money would not be worth it if you plan to build only one rifle, but building only one rifle is like eating only one potato chip when you’re hungry. Once you complete that first rifle, your enthusiasm feeds on accomplishment and draws you into planning your next rifle…or two…or three. I warn you, it can be addictive.
Of course, if you are strong-willed enough to stop at one rifle, you can go at it with only mallet and chisel, but it is a long and tedious job. If you choose that course, draw a straight line where you want the center of your channel to be with the appropriate amount of cast-on or cast-off, then drill out three-fourths of the wood with a set of Forstner bits on the drill press (or even using a good electric hand drill). Forstner bits do not wander once they are started. They leave flat-bottomed holes that are easy to clean up. For a straight sided barrel, say one inch diameter across the flats, choose a 15/16” diameter bit to remove the wood down to where the oblique flats start and then use a 3/8” bit to drill down to the bottom flat. A barrel that is 1” across the flats has a 0.414” flat width. A 15/16” barrel has a 0.388 flat width. For thinner barrels than that, chose a 5/16” Forstner. That combination of two bits will leave a profile similar to Fig. 3. The corners can be roughed out for the bottom oblique flats using a 5/16” chisel. The final shaping can be done using a scrap section of barrel equipped with a handle. Tom Harbin made for me a nice set of finish scrapers for seven different barrel diameters. If the facing edges are kept sharp at the corners, they will take out a lot of wood in a hurry (Fig. 4). If you wish to use some bedding compound to seal the barrel channel against moisture and warpage (a good idea for a fullstock longrifle), leave a little extra space under the bottom flat.
The fastest and most precise way to inlet a barrel is using a milling machine. If you are so fortunate to have a mill (or a friend who does), then by all means use it. You might want to read “Machine-Inletting the Swamped Barrel”, Muzzleloader, Jan/Feb. 2009, p.46.
Next time, let’s get that tang inlet into the wrist.