Routing barrel channels -- a long how-to

[mongrel]

It's no secret that I use power tools for every process I can contrive a way. I'm not one for building a single gun every few months -- I work on a semi-assembly-line basis and for me it's literally true that time is money. What follow are a couple of examples of how a combination of a router and a table saw speed things up.

The barrel inletting in particular is also a worthwhile consideration for anyone who owns a router (or needs an excuse to buy one ) and a few basic bits, but doesn't intend to build guns on a wholesale basis. I use a 45-degree bit, a straight bit, and a 1/2" roundover to get a barrel channel cut and the forend roughly-shaped. These have multiple applications for home woodworking (think pieces of furniture, shelves, etc) and, along with the basic router itself, are worthwhile investments.

I actually own eight routers, if you count the Roto-Zip with a sort-of router base I use to cut the slots for single triggers. I could justify nine, since I have to pull the 45-degree bit out of one and substitute a 9/16" roundnose bit when I inlet round barrels. I could further justify a tenth and eleventh, since I use three nearly-identical 45-degree bits -- one as-bought, and the other two with different amounts of the points ground off -- that are each dedicated to 3/4" or 13/16", 7/8", and 15/16" or 1" barrel channels.

When working with maple in particular, but also with walnut, cherry, or other suitable gunstock (or furniture) woods, don't go "on the cheap" with router bits. Buy carbide and train yourself not to wince when you see the prices, particularly of the roundovers. High speed steel bits cost a fair chunk of change, too, and on a really hard chunk of curly maple you will fry at least one HSS bit before getting the barrel channel cut. Carbide is expensive because it lasts.

What follows only works for straight barrel channels. To inlet a swamped or octagon-to-round barrel, determine the diameter of the barrel at its narrowest point, and cut a straight channel of that dimension. I use the router next to widen and deepen the channel, where it's needed, but I don't try to do a finished job of it. On swamped and octagon-to-round barrels it is necessary to finish by hand, which is a tedious process and the reason my labor rate goes up when anything but a straight octagon barrel is called for.

I should also mention that the original idea for this method was taken directly from the last chapter of Jim Carmichel's book "Do-It-Yourself Gunsmithing". I've adapted his original method to a variety of purposes, but the basic concept of using a router with a stop on it to cut octagon barrel channels, I took from him, and I would be remiss to not give credit where credit is due.

To begin with, the entire forend of the stock blank has to be of a uniform width and perfectly squared-off. I will actually take rough blanks that have warped or twisted slightly and spend a fair amount of time working them straight and square with a combination of jointer, table saw, planer, and hand plane, and having achieved that will immediately lay out the sort of stock blank seen in these pictures -- very close to finished profile -- and cut it out on my bandsaw. I don't leave a blank in this shape sit for too awful long -- this would increase the chance that the wood would begin warping and twisting again.

I trim my blanks to width, back into the wrist area, calculating as follows: The diameter of the barrel to be used plus the thickness of the lock and sideplate panels. Most locks, such as the Silers, require a panel of slightly more than 1/4" thickness. I allow for 5/16". The lock and sideplate panels ought to match -- though, not to go off on a tangent, there are a number of original rifles on which they don't, and they were done that way on purpose. I can't bring myself to mis-match my panels. So, in the vast majority of cases, I will be working with a stock blank trimmed to between 1 1/2" and 1 3/4".

When doing a mess of rugrat rifles, which almost all use 13/16" or 7/8" barrels, I trim everything to 1 1/2" width and divide the blanks into 13/16" and 7/8" lots, so that I only have to set-up my tools once per barrel diameter.

I also leave at least 2" of extra forend, because routers have a nasty tendency to tip and chip-out wood at the very ends. By leaving some extra wood out past the muzzle of the barrel, any mishaps at the tip of the forend will be cut off.

What we have in the following pictures is a blank trimmed to 1 1/2" width, which will be inlet for a 15/16" diameter barrel. As seen in this first picture, I mark the top of the forend for the barrel width, centering the barrel so that the router can be used from both sides of the blank without adjustment. In this picture the initial cuts have already been made, and it will be noted that they are well inside the marked lines. This is just in case the bit should wander in this hard wood -- possible even with very good routers. It will also be noted that there is a stop mounted to the router base, riding along the edge of the forend. More on this in a moment.


The stop referred to above is attached as shown in the next picture. Measure VERY carefully from the far edge of the bit to the stop, and subtract about 1/16". The purpose of the stop and the way it's attached is to prevent the bit from going OUTSIDE the lines -- if it jumps it can only jump INTO the barrel channel. Additionally, DO NOT attempt to make a full-depth cut into the forend. Make an initial cut about 1/4" deep and then adjust the router bit to full depth -- unless the wood has indicated you need to make another cut deeper but still not full-depth. The harder the wood, the greater the likelihood this will be necessary. The bit can chatter or vibrate loose in the chuck if this caution isn't heeded. I've had bits work their way out and end up eating right through the bottom of the stock blank.

It will be noted that the center of my router seems to be missing. I removed it to give me full visibility of the bit contacting the wood. A tool is only as good as the quality of work you can do with it, and if experience says to modify something -- modify it.


Here we see the router bit snugged up against the far edge of the barrel channel, opposite the stop. I take my cuts in at least three section, owing to how whippy the forend of even a stock blank can be on a longrifle. I've had entire halves of forends snap off when I tried to overextend a cut and the bit grabbed. Not only are curly maple blanks expensive, the forends don't break off square -- they shear into short spears and at that point are suitable only for firewood, or on the off-chance there's a vampire needing staked.


Here is a second router (or the first one after a bit change) set up with a straight bit and a stop that's positioned so the bit is in the dead-center of the barrel channel. This is set to a depth of a hair more than half the diameter of the barrel, to remove the inverted "V" of wood left between the 45-degree cuts.


All things working as they should, this is the final result -- a barrel channel ending half the diameter of the router base away from the breech portion of the stock blank, and a barrel that lies nice and not-quite-snug in the channel. Allow just a hair extra width to the channel; the wood is going to absorb moisture from the air and also whatever finish you apply, and it will swell enough that a barrel channel cut snug at this point will be too small for the barrel on the finished rifle.



What follows next is up to the individual builder. Obviously, that last 4" or so of barrel channel has got to be cut in. If you're not somewhere between pretty derned good and expert at freehanding straight cuts with a router, use chisels. This close to finished is NOT the time to have an excessively high opinion of your own ability -- routers never make small mistakes.

I designed and built a jig specifically for this job, using the router. The third photo shows why I removed the center portion of the router base, on the machine that my 45-degree bits are used in. The router is sitting about 1/2"-5/8" above the forend and blocks out a lot of shop light; removal of the base center is the only way my 50-year-old eyes can clearly see what's happening down there.




These next several photos show the barrel channel taken as far as the router can go, being finished with chisels, and finally the end result -- a nice, square breech section and a barrel nestled happily in its new home.





This next process involves a bit you won't find in any hardware store. I saw it in a Woodworker's Supply catalog and knew I had to own it. It's only useful if you intend to cut a lot of ramrod grooves, and it's expensive -- over $40 if I recall correctly, and that was roughly ten years ago. However, it cuts a perfect 3/8" half-round groove. Setting the bit depth to precisely half the width of the stock blank, turn the blank on its side and set the base on the upper edge of the wood, and go for it.


Next we trim the forend to somewhat close to finished width. I like to leave slightly more than 1/8" thickness of wood to either side of the barrel channel, which is actually too much, but it's far easier to remove additional wood in final shaping than it is to try and figure out how to replace too much wood removed by mistake.

For those who might be curious, this was the process I was performing, on multiple stock blanks, when I stuck my left hand in the table saw. I was in a routine and got careless.

I carefully measure where I want my cuts to be and mark the underside of the forend accordingly, at the muzzle end. I DO NOT pay the slightest attention to the ruled blade guide of the saw. The cuts have to be in the right place. This is established by holding the end of the stock against the guide and blade (NOT running!) and visually checking, leaving a slight bit of excess wood. Turn the saw on and let it just kiss the wood, then shut down and check where the cut is. Another reason I leave several inches of excess out past the muzzle of the barrel -- any mistakes are in a waste area and can be cut off.

If you trust the ruled guide and happen to be off 1/32" in the wrong direction, the entire stock blank is very likely ruined, and at this point it is NOT very consoling to know you had the saw set to where the numbers said was "right". What matters are results, not the "correctness" of the set-up.


This roundover bit, set deep inside the router base so that the bit's edge barely touches the wood, removes material along the upper edges of the barrel channel. Set full-depth, it likewise removes the corners of the blank along the lower edges of the forend. Be very, very careful, working out toward the muzzle end -- by now the wood is super-whippy and that bit will convert the forend to kindling if it gets to chattering.


Once the edges of the forend are rounded off, the wood can be trimmed back to 1/16"-1/8" back of the muzzle of the barrel -- how much depend on whether or not a nosecap is to be installed. I don't extend either my cap or the bare wood (if no cap is used) to perfectly flush with the muzzle. I prefer it be about 1/16" back of the muzzle. Your mileage may vary -- meaning do it as seems best to you -- but here is the final result of all this long-winded process.


All that remains, at this point, is drilling the ramrod hole, but that needs to be dealt with as a separate topic.

Hopefully this has been useful.

[Red Badger]

Lots of information to take in there!   Thanks Mike!

[pathfinder]

After inletting @ 26 Swamped barrel's,15 Round barrel'sand @ 14 straight barrel's,I now let Knob Creek or Jack's Mt. stock's do the most tedious part of gun building.

That's a great tutorial Mike! Thank's and I hope it inspires others to take up the trade. It really isnt that hard,IF you study the gun and how everything relates to each other. I dropped out of Med School,so if I can do it,anyone can!

[gunmaker]

Simply amazing how great mind's always think alike !! I've been doing about the same process for quite awhile, even use heavy angle irons for guides as well. And for sure "yes"  better be careful with both the router & your tape measure. Good post Mike thank's.  ....Tom

[mongrel]

Like I said, and I know this will offend some people who worship measuring devices -- tape measures can get a body in trouble. Routers and saws both can torque out of line, under hard use (such as cutting through maple). Best to start off cutting the channel too narrow and shallow and then enlarge and deepen it in one or two additional passes, when the bit is just shaving the wood instead of hogging through it.

Or always be prepared to increase the barrel diameter to be used in that stock to the next size up....

[BruceB]

As soon as the weather improves a bit and I can set up outdoors I have a couple channels to cut. I use a router table with the fence on one side and a large piece of angle iron to use as a fence on the other of the stock. And yep, I run it thru 6-8 times because trying to do it with 2-3 passes makes it difficult and packs the channel with chips. Then I roll it over change bits and cut the ramrod channel. It works for me. It may not be the most efficent nor historically correct manner to accomplish this task, but when the gun's done who will ever know?

[mongrel]

How can it not be historically correct?

Water-powered saws, grindstones, hammers, and so on date back to the moment they had the time and leisure to build mills beside rivers and streams, in this country.

Electricity is largely generated by water.

Hence, electric power tools are water-driven and absolutely 100% historically correct.

Funny how the logic holds up even when the conclusion is utter 

[BruceB]

OH the electricity is A OK, but I think Black and Decker did not manufacture router tables until the mid 1850s

[pathfinder]

It was "Ye Olde Black unt Decker" then!

[BruceB]

I think it was Black unt Dickert   

[Red Badger]

10,000 unemployed people out there and you guys are trying to be comidians...    whats worse you are better than most of the ones I have seen lately!

[BruceB]

Pathfinder started it!!!!! 

[mongrel]

Besides, in this economy, any of us who have jobs are liable to be unemployed tomorrow, and we know it. So our comedy routine is just good old-fashioned gallows humor.

As the saying goes: When Death smiles at you -- smile back.

[Dogshirt]

As the saying goes: When Death smiles at you -- smile back.

I give him BOTH middle fingers and dare hdo his best! Someday I'll lose, but untill then I'll LIVE on my terms! HOKA HEY!

[sweed]

Mike
I know your going thru the ol change right now, , good for you, but when you think you'll get around to drillin' that R R hole? Oh. BTW Your shop looks just like mine. If you insert just ONE more thing, you won't be able to move, and If someone moves just two things,   any two things  you won't be able to find your ars w/both hands!!