Building a Chunk Gun

[okieboy]

  I shot these and placed a 12" rule in so you could get a feel for the size. This is just lumber yard pine. I did put a coat of finish on it and a piece of leather on the bar to make it more comfortable for Sue. This would still meet York rules that the gun be able to move forwards and back and side to side.
 Please note the scale on the inside (of both sides) to help judge adjustments and help rough level it. Not a bad idea though to have a torpedo level in your box when you get down to shooting for money or pies.

[okieboy]

 Sorry guys, totally forgot to show you the built in wrench pocket. The wrench has the box end cut off to make it a single end wrench. The measurements are : 15" high x 11" deep x 16" inside to inside. I didn't want wing nuts for this particular application, but it is probably 6 of one, half a dozen of the other.

[okieboy]

 It is easy to find instructions for hand cutting dovetails, so I won't go into great detail. I made the basic slot with an end mill in my drill press, holding the barrel in the cross slide. The marks that we scribed on the bottom flat of the barrel are used to center the end mill from front to back and then a series of progressively deeper cuts are taken across the barrel until the slot is deep enough. This barrel has lots of meat, so I made the slots about .065" deep. I checked my progress with a depth micrometer since I have one, but a caliper would have been fine. A drill press is not a milling machine, so each of my passes is small, .010-.015" at a time. What I like about this method is the nice flat bottom produced. I have cut plenty of dovetails with just a file, but getting an even depth to the slot can be trying.
 The picture is of the drill press setup, though in the picture the slot shown is the front sight slot, which is handy to cut now as it is the same setup.
 The second pic shows the dovetail angles cut into the slot using a homemade dovetail file ground smooth on one side. I re-polish this smooth side on a diamond sharpening stone from time to time.
 The final picture shows the installed underlug. I fit up by removing material from one end of the lug, filing small start chamfers, tapping it in and fitting some more till it seems right. I fit the lugs pretty tight, driving them into position with a punch and small hammer, check the centering carefully and then peen down the edges of the dovetail on both sides of the lug.
 We will look next time at inletting the lugs, but let me mention now that I install one lug, inlet it and then the next and so on. I start at the breech end and work towards the muzzle.
   

[okieboy]

 Inletting the lugs is pretty straight forward. I mentioned that we start from the breech end, we "stain" the underlug, place the barrel in the channel, tap the muzzle with our mallet to seat the barrel's breech end, then tap the barrel's top directly over the lug. This should give us a good transfer. It is not unusual for me to sometimes highlight the edges of a transfer with a sharp pencil to make things easier to see.
 Now we can do substantial material removal with the mortise chisel that we made from the lug material. I see no harm in making the lug mortises a bit long front and back.
 We can check our progress reasonably well with a depth gage, and as we get close to depth we deepen the mortise by scraping. Although there is no real harm in cutting through our .200 web allowance to the ramrod groove, it is nice craftsmanship not to.
 In the final fitting we need to have stain not just on the lug, but on the barrel bottom flat. When we stain the bottom of the barrel channel, we know that we have mortised deep enough. When coaxing pieces together like this, I sometimes tap with a mallet (in this case a Lixie) and sometimes clamp with a small c-clamp.

[okieboy]

 Now we get to drill the pin holes through the underlugs, this is an operation that causes some people to hold their breath, but the way we are going to do it is pretty foolproof.
 I use a drill press with a vise. As you can see in the pictures, I am the proud owner of a $30 cross-slide. Before the cross-slide, my regular drill press vise cross-slid by way of my mallet!
 The vise has two jaws, a stationary jaw that is part of the vise body and a moveable jaw that we tighten to hold our work. We are going to adjust the location of the stationary jaw in relation to the drill such that when we clamp the top flat of the barrel tight against the stationary jaw, the drill will pass right along the bottom flat of the barrel.
 I made my setup by clamping a piece of 1" barrel in the vise (we could have used the actual barrel, but a short piece does the same thing and is easier to handle). The bottom flat of our piece is blacked by a felt tip; the pin sized drill is in the chuck, we turn the motor on and start adjusting the barrel towards the drill, simultaneously making the drill go up and down, until we see that the drill has rubbed against the barrel, making a shiney mark. In machining we call this coming to "scratch". Now we lock the vise/cross slide to prevent changes of location in this one direction.
 Now we can put the barrel/stock assembly in, top flat against stationary jaw and drill any number of pin holes, all at the bottom of the barrel.
 As to specific drilling technique, I start by putting a center drill in the chuck and use this as a center point to move the assembly muzzle to breech direction, until aligned with the layout lines we drew earlier. Then we drill a start with the center drill about .060-.075" deep, stop the motor and change to the pin sized drill and drill away.
 Once we have drilled the first hole, we unclamp the movable jaw, switch back to our center drill and do the same thing for the next hole.
 It is not important to drill completely through the stock, in fact it is probably a bad idea because of drilling into your vise. It is good to get through the underlug though. Later, on the bench we can complete the holes by holding our pin drill in a pin vise (another little tool that is hard to live without) and turning the drill with our fingers. Not fast, but sure and this enables us to drill a hole very nearly as deep as the overall length of our drill bit.   

[okieboy]

 With the under lug pin holes drilled, there is one small task before starting on the lock. That is making pins that are easily removable while we are working on the gun. I make my pins from music wire, which is a very hard wire that is bendable. Music wire is generally 1095, which is a hard spring steel. Music wire is handy for pins, springs, and tiny chisels. I bought an assortment of music wire out of a hardware store back when there were nonfranchise hardware stores, now one has to go to an industrial supply or specialty metal supply.
 Place the wire in your vise about 1/2" above the jaws and bend it to 90 degrees with your favorite hammer. Cut it off with the corner of a grinding wheel, put a good chamfer on the end and you have an easily removable pin.






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[okieboy]

 I hope you guys caught the pattern for making a mallet that I put on Mattole's topic "cost of tools".

[okieboy]

 With the barrel pinned in the stock, the next step is inletting the lock. The first step in inletting the lock is disassembling the lock, so that we can prep the lock plate and inlet it first.
 The first step in disassembly is to have some lidded plastic storage containers on hand in the shop, the cheap ones from the grocery store are fine, but you are advised not to skip this step!
 The next step is to put the lock on full cock and snug your spring vise onto the main spring. You want to make sure that the vise has a good purchase on the spring. I actually ground the angle on the top of my vise to make it fit better. I would advise not trying to substitute something like a visegrip for a spring vise.
 Once the vise is snugged up, we trip the sear, push the hammer forward and wiggle the main spring free. After it is out loosen the tension on the vise till the spring comes free and put both in the small parts storage container. Disassembly work is a good time to have your bench neat and orderly.
 Next loosen the sear spring screw, pop the sear spring loose from its mortise, then finish removing the screw and spring. You may notice that I am using gunsmith screw drivers and these are tools that I wish I had bought sooner.
 Next we remove the bridle screws and bridle, being careful as this is when we remove the detent from the tumbler.
 Turn the lock over and remove the hammer screw.
 In removing the hammer from the tumbler we don't pry the hammer, we punch it loose. It is handy to have a punch block, which is just a scrap of wood with a suitable sized hole through it. We choose a punch which fits inside of the threads, not on top of the threads and tap the tumbler free with a small hammer. The punches that I am using were expensive, but not as expensive as the  frustration and damaged work that cheap punches produce.
 Next we will prep the lock plate.

[okieboy]

 Before inletting the lock plate, we prep it a little. This consists of removing the casting surface by flattening the outside face of the plate and squaring and smoothing the edge of the plate(as I have said before I do not favor the draft angle on the edge of parts to be inlet as some others do).
 The face of the plate is flattened and smoothed by flat sanding on a granite tile after being rough flattened with a file. Aluminum oxide paper worked much better on this casting than wet or dry.
 The edge of the plate is filed square with a smooth file and will get draw filed and polished with sand paper wrapped around the file. What I want to show though are the two different ways of filing an edge. Simple straight cross filing works well on the straighter portions of the lock, but when we get to the rounded ends laying the plate down on a flat piece of scrap and turning the file up on edge gives us much better control to produce smooth curves without facets.
 I also want to show how handy a woodworkers clamp is. By clamping it in your vise, you can raise the work up and you can clamp at 90 degrees to your vise.

[okieboy]

 I will try to explain this being my preference (altough I don't presume to think it is right for everybody else).
 First let me say that on the tang tapering might have made it easier, but I don't consider not tapering to be the root problem. I consider the root problem to be that handling a 9 pound 48" long barrel is difficult and that the tang being longer increases any errors that handling produces. Meaning, that I should have used more care and worked more slowly than I did. For me not as much the wrong technique as poor execution of my chosen technique. There is no excuse for the poor execution.
 I should also say that the tang issue is with one side, the back of the tang fits up simultaneously with the back of the tangs front tap and the back of the tang does have a draft angle because of the geometry of the tang. Please note that the back of the tang and it's angle run perpendicular to the grain of the wood. That is an important distinction for me.
 There are two problems for me with tapering parts and these problems apply more to thick parts like tangs, trigger plates and locks, less to very thin parts like decorative inlays. I have drawn an exaggerated picture of my two objections.
 One, tapering means that the bottom, which you trace to inlet is smaller than the the top, so as you deepen the inlet, you must also make it wider, this is difficult to do accurately by chiseling down, but might be done well by scraping the sides of the mortise. Is that what you do?
 Two, tapered mortises on thick parts that are later "snugged" with screws act as wedges applying wedge force in line with the grain. If we want to split wood, such as kindling, we apply a wedge (hatchet) along the grain. Now think about where most of the cracks are located on old rifles that you have handled; often they emanate from the lock mortise or tang mortise.
 I think you would find most of my inlets quite acceptable, my lock is already inlet and the plate fits closely enough that it has to be pulled out. When I inlet I mark the part edge closely mostly using very sharp Exacto knives, but then I "set in" with special inletting chisels. These are completely flat on one side (flat side to the outside) and thin as razor blades. I tried to show the thinness in the picture, but most of what you see in the side view is shadow. You may also notice that there are four different cutting widths. As the cutting width gets narrower, the chisel can deal with a more curved line. The narrowest cutting width can go around a suprising small curve (very slowly), without producing faceting.   
 I have tried to take a picture of the line being cut for the trigger plate, but it is not easy to see.
 I hope this makes some sense of my approach and would be glad for you to take exception to any and all of it.

[okieboy]

 In relation to inletting depths, I will go ahead and show you this tool that I made to control mortise depth on my lockplate inlet. Yes it looks suspiciously like a depth gage from Sears that has had the stem shortened and sharpened. Let me warn you that it isn't perfected yet, it did not want to cut when pulled as a scraper, so I slid it from side to side and it cut thin little witness marks, giving me an indication of needed material removal.
 Maybe I've got it too sharp, or maybe the "cutter" needs to be narrower. If you make one of these to try out, be aware that the surface of the wood in contact with the gage base can get scuffed up a bit.

[Jim Kibler]

The typical taper on sides of parts being inlet is pretty slight.  It doesn't create any substantial wedging effect.  What it does is help create a tight fit on parts.  Give it a try.  It's the way to go.  As far as marking the outline to cut, here is a technique to consider.  Taper the edge of your part appropriately.  Put part in place and outline with a sharp scribe.  Outline slightly inside the scribed line with a small veiner.  Stab in outline with appropriate gouges and chisels by placing the cutting edge directly in the scribed cut.  The veiner channel allows a place for the wood to be displaced in the stab in process.  Done well, this process creates a tight fit with often little or no further fitting on edges.

[okieboy]

 The inletting tools in the aboe post are made from 1/16x1" O1 tool steel. You cut off a piece about 4.5" long, then cut it into two diagonally. Most of the work is done previous to hardening. Patience is required at the belt sander or grinder not to overheat the steel, never wearing gloves is helpful in this. When it is too hot to hold comfortably cool it in water; if it sizzles, slow down.
 Harden at 1450-1500 degrees, I just heat it to a bright yellow. Get the heat up back from the cutting edge and then work it up to the edge. Quench in motor oil, there is a picture of my safety first oil quench set up earlier in this topic. Oven temper at 425 for an hour. Be sure and wash the oil off before tempering if you have a wife. Expect hardness of about 58/60 Rockwell C.
 When you sharpen and polish after heat treating, do not forget to flatten the flat side in case there is any warpage and it needs to be polished anyway for proper sharpening.
 The Home Mechanic's friend McMaster-Carr supplied my O1 and I keep some various 18" long flats on hand in my shop as it is so easy to work with and useful for so many little things. One of the things that I will make at the end of this build is a small flat nipple wrench/ turnscrew for pouch or patch box.
 Let me know if you make some of these, they are only used for setting in, but they do excel at that. 

[okieboy]

 Now that the lock plate is ready we can start inletting it. The bolster goes in first. I put in a powder drum, extend the line of the top of the forestock with a pencil, lightly stain the bottom of the bolster, bump the plate against the powder drum, align the top of the plate with the line of the top of the forestock and give the plate a rap with a mallet to get a good transfer. Removing wood from the bolster mortise (after removing the powder drum) goes fairly quickly as the final depth is set by the side of the barrel. Note the cotton in the tapped hole keeping wood chips out of the barrel. Pretty obviously, when you get to the point of cutting through the wood to the metal of the barrel it is a good idea to have an "abuse" chisel to spare your good tools. This can be a cheap chisel or even just a sharpened piece of steel; I have a bunch of salvaged steel leaf rake tines that are handy for such tools.
 On a percussion, making the plate support the drum makes the impact of the falling hammer transfer into the plate, reducing stress on the drum. I have read that some people install the plate first and then locate the drum from it.  My plan is to locate the plate mortise from the drum. You can see from the clamps in the picture that I went to some bother to pull the plate against the drum. Also, the barrel is pinned in place, but the tang screws are not in yet; when the tang screws are tightened, they will help pull the barrel and drum down onto the plate.
 I outlined the plate onto the stock with a knife and in some places an inletting chisel.  I remove the plate an set in (deepen) the line with inletting chisels. Now I start removing waste from the mortise.

[okieboy]

  Someone put the effort into teaching me much of this; I have tried to grow from those basics and consider it a privilege to pass this on to someone and hopefully, they in turn will share with someone else.
 On to building! With our bolster inlet and the plate traced, we concentrate on getting the stripped plate let in to depth. We roughly lower the bottom with a small bent gouge and carefully work around the out line with small very sharp chisels and in certain parts of the work, small scrapers. I will post some tips on making small scrapers and considerations in sharpening them in a separate entry, but will mention now that scrapping mortise bottoms can be done nicely by holding a chisel low on the blade at 90 degrees to the wood and pulling it along the wood. It is best if the chisel is very sharp.
 Some things to note. The plate can get very tight in the inlet, at first there is space under the bolster for some gentle prying, but later I fit a little hardwood dowel to the tumbler hole to help lift it out. There is no problem removing some wood under this hole as the tumbler and bridle are going to require wood removal from this area.
 If we want to remove some of the tightness from the mortise, we can do this slowly by scraping the sides of the mortise, but we should be more aggressive on the top (powder drum side) of the mortise and less aggressive on the bottom. this will help keep the plate snug against the drum.
 With some careful measuring and simple math, we can determine how deep the mortise should be from the nice flat side of our stock. Then we can set our depth gage/scraper to that depth and check our work. If you look, you can see witness marks made by this tool. I can remove material until the marks start disappearing, mark again, remove wood again until full depth is reached. 

[okieboy]

 Now that the bare plate is let in, we start adding parts to the plate and staining and inletting them. We start with the "shorter" parts like the sear spring, then the tumbler, then the bridle, then the sear, and finally the mainspring.
 I inletted the lock "stationary", at halfcock without the hammer, then inletted the triggers, then went back and finished the "dynamic" lock inlet with the hammer and moving through fullcock to full down. It surely doesn't have to be done this way, but it seemed pretty handy. During most of the dynamic inletting the triggers were not installed, a small dowel being used to push the sear.
 I wanted to show how pencil marks are used to help define the edges of the relief cuts. I also used my crank drill (every body calls them "egg beaters") and a 1/4" brad point bit to deepen the sear hole, the tumbler axis, and quite handily the front end of the mainspring mortise. These crank drills can generally be had for $5/$10 at flea markets. The fact that they can go faster or very slow under complete and immediate control makes the a great tool for our work. A lot of my countersinking is done with a crank drill. The sear hole, by the way, ends up being square by the use of a 1/4" bench chisel. I think the square hole is easier to check for interference and works well with the trigger mortise.
 One thing that I wanted to say, but don't want taken the wrong way is that because this is a heavy stock with plenty of wood (because of the 1" barrel) I feel that I can be a little bit more liberal in in my reliefs for the moving parts of the lock and triggers. I am not suggesting sloppy work. This is a competition gun and interferences with the moving parts can't be tolerated. Also all the mortising terminates in radius-es, we will leave no pointy terminations, that is we leave nothing that might easily generate a splinter to baffle us at the big shoot.
 I threw in a picture of the benchtop and tools at the time of inletting.
 Next we will locate the triggers.   

[okieboy]

 I think you are looking at the old Sargent handled scraper. This has a four position blade, though I currently sharpen only one edge. I sharpen this like a chisel, not like a cabinet scraper. though it could be done that way.
 The angle of the blade to the handle can be adjusted. Hopefully the disassembled picture makes the ball joint understandable.
 I have never used this on gun work, my intent was for furniture work. Although one can use a tool on anything one pleases, I believe that the most common use of this type of scraper was scraping the tops of butcher's blocks.
 This tool is vintage, but Lee Valley sells a similar new tool.

[okieboy]

 The triggers are located by the sear. I am using a set of Davis #6, which are double lever and the adjustment screw marks the center of the two levers very well.
 I did a rough outline of the trigger plate on the bottom of the stock and then within this outline cut a narrow mortise down into the sear mortise. Then I could install the lock, see exactly where the sear was and mark a line with a pencil.
 After this I calculated the distance from the edge of the stock to the edge of the plate, set a marking gauge and scribed a line a little shorter than the length of the plate and started setting in. I choose this way because the plate is thicker in the middle. I could locate the second side of the plate from my scribed and relieved line, and work the middle of the plate into the stock, then carefully maintain the adjustment screw hole on line with the sear line as I let the rest of the plate in. During part of this work I found it handy to clamp a stop onto the stock to easily maintain positioning.
 From there it is just like the lockplate, plate to depth then add a part and inlet for it. Finally when all of the trigger is inlet, set and trip the well stained triggers and look carefully for interferences. After this try them with the lock to assure ourselves that we have a functioning system.






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[okieboy]

 I forgot to show you the secret trigger plate removal system, which is very handy to use as the plate gets deeper in the mortise.

[okieboy]

  I want to show these pictures related to triggers. The trigger plate did not quite match the curve of my wrist, so I decided to tweak it a little. First I put the back portion in a wood vise and closed the vise a couple of times, making no discernable change in the plate. Then I put part of it upright in a wood vise and tapped it with a Lixie mallet. No change. Tap a little harder. No change. Tap a little harder yet and I got the "change" you see in the photograph. Surprisingly, I chuckled about it (not always the case with me).
 Although the plate looks machined from barstock, it is an investment casting which "can be adjusted slightly", so I guess I adjusted it slightly too much.
 If you order the replacement plate, you get the raw casting shown, which I will work on some other winter. I ended up just getting another set of triggers. I improved the fit by shortening the plate from the back and will have to do some minor blending of wood and steel.

[Jim Kibler]

From your pictures it seems there is a shrinkage voide on the casting.  This coincides with the gate location and based on the part geometry, it is likely the last area to solidify.  This is where shrinkage voids often occur.  Bottom line is that your original part and the replacement with this condition should have never been supplied. 

[okieboy]

 You make a very good observation. I went back and examined all 3 plates and tried to make a better photograph as I think the ones I showed may be somewhat misleading. There is a void there, but all of it appears by design to incorporate the wire front trigger spring used. I would prefer the old flat style spring that secures by the mainspring screw, but that isn't how this trigger set was designed.
 This is the best photo I could get of the cast in pocket, what do you think?

[okieboy]

 With the triggers inlet, we can move to installing the tang screws. The tang gets two screws, one into the trigger plate and the back one is a wood screw. First we are going to find the spot where the screw will come through the trigger plate. The trigger plate is going to get three screws, the tang screw,a screw to hold the front of the trigger guard on and a wood screw at the back.
 We mark a line on the trigger plate just ahead of the most forward sweep of the top of the front trigger. Then we position the trigger guard (this is not a roomy trigger guard) such that the inside of the back of the bow misses the rear trigger (in set position) by about .100". I didn't notice till tonight that I placed the guard against the wrong line when I set up the photo. Please imagine the guard one line forward of where the photo shows it. So we have the front of the trigger plate divided into two areas, one for the tang screw and one for the trigger guard screw.
 We transfer the two lines onto the bottom of the stock and " wrap the marks a little onto the lock side. the little circle between the two lines marks where the tang screw will come out. You can see that I have clamped a die makers square midway between the two lines to wrap the line across the top of the stock and the tang. In the last photo you can see the top of the stock and square. The latout line on the tang will get marked with a carbide scribe. The other line that you see on the top of the stock represents the location of the back of the lock bolster.
 Now all we have to do is cross the scribed line with a line dividing the tang from side to side and mark the intersection with a sharp center punch and we have our location.
 You might note that the square is flat rather than the more common beveled die makers square, which makes it handy for going around from one side to the next. I believe that I got this one from MSC some years ago.
 I apologize again for the trigger guard being misaligned in the photo, I've taken over 500 photos by this point, so I suppose I was due.

[okieboy]

 I deepened the punch marks with a center drill in my crank drill. I am going to drill for the tap screw by the point finds point method. I must admit that I have never used this before, but its logic is simple and elegant. The drill point is the"top" point and my "bottom" point is a center punch epoxied into a block that I can put in a drill vise. In setting up the drill, I roughly line up the drill and punch, then adjust the distance between them to about 3/8" more than the stock wrist is deep (1.900+.375=2.275). Now I align the two points precisely, Turning the drill's chisel point back and forth 90 degrees. Finally I set the depth stop so that the drill stops about 1/2" from the punch. I will drill with the tap drill first(a #21 for 10-32), so I place the center drilled tang hole on the punch and line the center drilled trigger plate hole up with the drill. I had Coach Mary supporting the barrel end and  moving it small increments to achieve alignment. Then I drilled , in and out as rapidly as possible. Then I changed to the "body" drill (a #10), turned the gun tang side up and repeated the process. The results were quite good. However the need for an assistant and depending on their steadiness is a drawback, but I don't think that I could easily have managed this without a helper.
 Next I moved the gun back into the clamps and tapped the trigger plate using the body hole through the tang and stock to align the tap.
 As the wood screw hole does not go through the stock, I drilled it with my crank drill by hand and eye. I also used the  crank drill to do the 82 degree countersinks for the screw heads. I started with a sharp countersink, but it gave me faceting chatter so bad that I hunted down my dullest countersink and it worked much smoother.

[okieboy]

 With the tang screws installed and tightened (pulling the drum tight against the lock plate), we can put the lock screw in. I layout the location for the screw on the front of the lock plate and punch it with a sharp center punch. Then I put the plate back in the stock and set it up in the drill press. You can see that I used my extension table and little jack stand to support the barrel end. Every thing gets checked with a small level. We add a set of clamps to seat the plate in its mortise and locate the center punch mark with our center drill. You can see all of the tools for this job at once in the third picture. There is a center drill, tap drill, body drill. and the tap in a tap handle. If you don't usually use center drills, I advise you to try them, they are very stiff for making the initial drilling go where you want it to, and they eliminate a lot of drill walking, especially in difficult drill operations.
 So we center drill, then change to the tap drill. With the tap drill, we drill down until we drill through the tang, then we switch to the body drill and drill all the way through the stock. When the drill was getting close to breaking through I held a piece of scrap wood against the stock to prevent chip out, but as there will be a side plate, this is a not a big problem anyway.
 Finally, I put the stock back in the clamps and the lock plate back in the stock and ran the tap through the stock to get perfectly aligned tapping. There are simpler ways to do this job, but this method is pretty much foolproof.