Author Topic: Building a Chunk Gun  (Read 130623 times)

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Building a Chunk Gun
« on: September 27, 2010, 01:50:23 AM »
I am building a new chunk gun and would like to document the process here.
After reading FG1's topic I decided to go ahead and get started. I an trying to photograph as much of the building process as possible and will try to post a photo representing each step. I build pretty much the way my mentor (Lee Good) taught me, but that's not the only way and I would welcome comments on the other ways of doing things.
 Obviously, it all starts with a plan and the first question of the plan is the barrel. The barrel is a compromise between length for sight radius, weight for steadiness and manageability for 13 shots. This varies for every shooter, and my choice was 1" x 48 " x .45. This translates to 9 pounds of barrel, and I weighed it to check.
 After the barrel is selected it time to start laying down the plan for the stock, so my first pic is me working on the paper layout. I have Ron Borron's drawings to help guide me as well as knowing the dimensions of my current rifle.




« Last Edit: March 30, 2021, 10:17:39 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #1 on: September 28, 2010, 04:19:14 AM »
Here is how I do a stock layout. I use two datums. A datum is a point, line, or plane from which things are measured. the first datum is the top of the barrel. The second datum is the center of the vent slightly ahead Of the vent. We start our first layout on posterboard (plywood later) by drawing the line of the top flat of the barrel completely across the paper, Line #1. We measure down 1" in this gun and draw Line #2, the bottom flat. Half way between these two lines we draw a line (that I managed not to label) and this is the top of the barrel channel.
 .200" (3/16" rounded up) below line #2 we draw the broken line #3 that is the top of the ramrod groove. .400" below this we draw the broken line #4 that is the bottom of the ranrod hole (3/8 ramrod). .200" below this we draw Line #5, which is the bottom of the fore stock.
 Across Lines #1 and #2 wedraw line A which is the end of the barrel. Then we draw line B which is the face of the breech plug. Then we draw line C which is the distance of the vent in front of the breech face. The circle represents the powder drum.
 I know many people place the vent location right at the face of the breech, then notch the breech face. I have disassembled old originals and know that this was common, but I do not wish to do this. My powder drum threads are 5/16 (.312), so I placed my vent location .190" in front of the beech face (.312/2=.156+.031=.187 rounded even).
 Next time we will work on laying out the wrist and butt stock from datum C. I know this is vary basic for some of the people on this forum, but some people are beginners without a personal mentor to walk them through this. Also this provides those with experience the opportunity to offer alternatives.
 

« Last Edit: March 30, 2021, 09:54:38 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #2 on: September 29, 2010, 04:12:47 AM »
 The next step in laying out is placing the lock. Let me explain: The vent establishes the location of the lock and thereby the location of the sear. The sear locates the triggers, and the front trigger locates the pull. The pull combined with the drop locates the buttplate.
 So first we draw in the lock using a photo copied and trimmed from Track's catalog: bless the good people at Track for their full-size photos. We draw a line down from the sear and allign our triggers with the line halfway between them. The lock that I choose was a Davis Goulcher and the triggers are Davis #6. I chose the Goulcher because I liked the size and think it will be very fast.
 Now we trace the triggers (the picture shows Sharpy lines to show up well, but the actual work is done with a pencil with a good eraser close at hand) with  care on the front trigger. From the point on the front trigger we sweep an arc 13-1/4" long for my pull.
 Next we draw a line 3" down from Line #1, the top flat of the barrel to give us our drop; small drop for a prone gun.
 Using the pull and drop we sketch in the buttplate and draw a line to the thumb spur of the trigger to establish the top of the comb. likewise we draw a line from the toe of the buttplate to the end of the trigger plate to establish the bottom of the stock (belly).
 Now we sketch in the top of the wrist and end of the comb. This is maimly by eye.
 Please understand that some of these steps are done once, the eye judges them as "Not fair.", erased and drawn again until satisfying.
  The nose of my comb is further forward than usual, but it looked right and can always be shortened.


« Last Edit: June 16, 2021, 12:31:42 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #3 on: September 29, 2010, 04:21:40 AM »
 Opps! Wrong pic. Thats me and Sweet Sue at a centers shoot. Hopefully here is the riht pic.


« Last Edit: March 30, 2021, 09:58:25 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #4 on: September 30, 2010, 04:09:31 AM »
 Is 3" of drop too much? Well, first off, I put the 3" on the layout to show how a layout is done, not to recommend it as the "right" amount of drop. But that being said it is the drop that I choose for this gun, which is being made to fit my body AND my shooting style. I'm sure some of the better shooters can elaborate, but shooting prone isn't just laying down. The angle between the axis of the gun and your body changes how you connect with the gun. Also how you position your elbows, forearms and hands in shooting position affects how you connect with the gun. I suspect that discussing variations of elbow positions may sound compulsive to some. It is. Chunk shooting is a delight to the obsessive complusive. Let me say that I am not yet a winning chunk shooter, but I hope to be within two years and believe that matches are won on the practice range. To that end it is not unusual at a practice session for me to get in shooting position ten times with Coach (my wife) taking a photo each time and later study the photos looking for inconsistanies.
 So, 3" may be too much for Billy and not enough for Bob, but hopefully about right for me.
 Which brings us to our next step in the process. Having drawn and redrawn the profile on paper until we are happy, we carefully cut the paper pattern out with our favorite craft knife and retrace it on a piece of 1/4" plywood and saw it out. You will notice that it is full length and that I left all of the "barrel" in and left the "buttplate" on.
 The first thing we are going to do with this pattern is trace it onto a piece of lumberyard 2x8 and saw it out, giving us (even left square) a decent prototype gun. We take our prototype, plop down behind our chunk and try out that drop and pull before committing to expensive maple.
 Actually when I "saw", I saw wide of the line and then sand to the line with a small belt sander, there will be pics of these set-ups later in the process.


« Last Edit: March 30, 2021, 10:15:10 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #5 on: October 01, 2010, 03:59:48 AM »
 Now that we have a pattern that we like, we are ready to buy wood. For stock wood I decided that I wanted the plainest hard maple (sugar maple) that I could get. I like the density and consistancy of maple. I wanted plain for multiple reasons: I like plain guns, plain wood cuts with fewer suprises than fancy wood and though I am not on a limited budget for this build, money saved on wood can be directed to other parts of the shooting program.
 I am fortunate that I live about 30 miles from Track of the Wolf. So, a Friday off, the pattern in the pickup and down the road I go. They showed me where the plain wood was racked and said pick what you like. So I pulled out all the pieces that were long enough, laid them on the floor, looked and fitted the pattern until I was satisfied with one. This picture is of me and the blank, which weighed 16 pounds.
 If I were going to get my wood elsewhere I think that I would make a full size paper pattern to roll up into a shipping tube and send to the wood dealer, though I would suppose most of them would choose well enough just by knowing the planned length of the gun.



« Last Edit: March 30, 2021, 10:19:44 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #6 on: October 03, 2010, 12:37:40 AM »
 
 So we have a pattern and a heavy clunky piece of wood. My next step will be to reduce the thickness of the blank. This will lighten it and get it closer to finished size, but importantly it is easier to saw and saw square thinner wood. The question is "How thin?" To answer this, we ask two questions: how wide is the buttplate and how wide is the barrel plus twice the thickness of the lockplate at it's fence. The buttplate that I have is 1.300" wide. The barrel is 1" and the lockplate is .265". .265x2=.530+1=1.530". I rounded this up to 1.600", which gives us an even .800" to centerline. This is obviously plenty of material for this buttplate, but a wider buttplate could have pushed our thickness higher.
 Since I am a longtime, well tooled amateur woodworker I get to take the waste off with my 12-1/2" planer. I take small passes, .010-.015" per pass and take passes on both sides, but if I like the grain better on one side I will take more off the other side. If you don't have a planer, it is very possiple that someone you know does, but before I had a planer I tackled chores like this with saw and handplane. where there is a will, there is a way.
 P.S. Saw the Bevel Brother's last article today in Muzzle Blasts: "After you feel like you've practiced enough, practice some more." I don't think that there is better shooting advice than that.
 
« Last Edit: March 30, 2021, 10:23:27 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #7 on: October 04, 2010, 01:50:10 AM »
 Our blank now weighs about 9 pounds and has two smooth parallel sides. Time to trace the pattern. We lay the pattern on the lock side of the blank, carefully position it, and clamp it in place. The extra minute spent clamping can save a lot of frustration. We trace around the pattern creating a line that will be easy to see.
 We remove the pattern, but as you may have noticed, my pattern is straight from the lock area to the muzzle; nothing cut out for the top of the barrel or bottom of the forearm. Here's why. We want a very good line marking the top of the barrel channel, so we measure over 1/2" (half a barrel) front and back and draw this line with a good straight edge(48" aluminum rule). From this line we measure over .200"+.187"=.387" rounded up to .400". The .187 being 1/2 of .375 since I am using a 3/8 ramrod. The ramrod drill is actually .390" for us obsessives. I draw a line 12" from the back of the barrel to mark end of the fore grip. Although we layout the bottom of the forearm now, we are not goint to cut it away now, but will cut according to the botton line produced by the pattern, This will leave the front of the stock stiffer and evenly stiff for letting in the barrel.
 We are ready to go to the bandsaw. Mine is a medium sized Delta. I read some entries on the board about getting some helpers when one bandsaws, but I made a 72" auxillary table for the bandsaw, which will also get used on the belt sander and drill press. I think you can see in the pictures that the table has a notch cut in it to fit around the saw blade and has a cleat attched to its underside to stiffen it.
 We will cut a little outside of our line and then trim to the line with a small belt sander, though we could trim with rasp and file.
 




« Last Edit: March 30, 2021, 10:29:02 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #8 on: October 04, 2010, 02:00:03 AM »
 I am not sure why I sometimes have problems getting the right pictures to post. Oh well try again.




« Last Edit: June 16, 2021, 12:36:20 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #9 on: October 04, 2010, 08:36:22 PM »
  I have done a layout in scale concerning the cheek piece. It will have a cheekpiece and I think that there will be plenty of wood. Cheek pieces don't take as much wood as one might think, depending of course on the cheekpiece. My opinion of cheekpieces is that they are mostly visual and at best provide some "landmarking" for consistantly locaing your cheek placement.


« Last Edit: April 01, 2021, 12:48:01 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #10 on: October 06, 2010, 05:44:51 AM »
  Our next step after sawing outside the line (how far outside depends on how well your saw is tuned and yourlevel of skill/confidence) is to belt sand to the lines. Here is a picture of my little Delta belt/disc sander. I want to comment on this tool. I've only had this a bit more than a year, but now I wish that I had had one long ago. I seem to use this all the time, squaring something shaping something, tapering something. When I made the wooden laps to radius the rifling to the face of the barrel I'm currently shooting, I made them by hand and eye on this sander. Some of the cutters and scrapers that will get used later in the build. Anyway we are going to clamp the auxiliary table that was on the saw to the belt table, support the front of the table with an adjustable saw roller stand that was handy( a sawed length of board clamped to the cleat would have worked too), check for level both lengthwise and across the table, and check the squareness of the belt support to the table with a good try square, twice!
 Sand in long slow passes and don't hurry. If the sander seems to cut too fast, go to a finer grit. Go to a coarser grit if it seems to just be polishing or worse burning.
 When this is done you can see that we have something with the flavor of a gunstock. What was originally 16 pounds is now 5 pounds even.
 Please note that we have not cut any of the buttplate fitting yet and won't till we have the triggers fitted, so that we can control the pull.
 We are getting close to letting in the barrel, but before we can do that we have to do the barrel prep work.
 



« Last Edit: April 01, 2021, 01:09:25 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #11 on: October 07, 2010, 04:32:25 AM »
  The clamps are handy as they adjust to any length desired. Well, my main bench is 11' long, so I guess there is a limit to how long a gun I will build.
 The clamps are Jorgensen #0, which have 8" long jaws, so they have a clamping depth of 4". The bases are 6 x6". To assemble, clamp the jaw fully closed upside down in your vise, drill and countersink through the base for the first screw. Install the first screw, then drill and countersink for the second screw. Install the second screw. I sometimes swipe screw threads with a block of bee's wax; I do not use soap.
 Now remove the screws, paint the bottom of the drilled jaw with 2-ton epoxy( you want the jaws spread apart at this point) and "clamp" you glue-up by reinstalling the two screws. Let set 24 hours and you are equipped for gun building. At this point some someone is thinking "There was no need to install that second screw before gluing." I like to precut the threads and finding trouble with a screw after the glue is smeared is no fun at all.
 Speaking of smearing glue, here is a tool tip for you. I mix epoxy and apply epoxy and wood glue using bamboo skewers from the grocery store. I actually keep two sizes, break them into handy lengths, trim different points and flats on the end as needed. They are also handy with a little cotton twisted on the end to make tiny or very long swabs.
 

« Last Edit: April 01, 2021, 12:52:24 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #12 on: October 09, 2010, 02:31:20 AM »
 I have never been as excited about castoff as some people seem to get and as slowly and carefully as you get into position with a chunk gun I don't see it as contributing much.
 I favor a pinhead front sight with a donut spotter. I make my own rear sights and the one on the gun I'm shooting in the pictures is about the fifth one I tried. The thing is that the spotter, the front sight and the rear sight have to work together, so a different sight may demand a different spotter and vice verse.
 The next step is preliminary prep of the barrel before letting it into the stock. This means draw filing the flats and a first polish. The draw filing is done because it will change the size of the barrel. I know this will only be .002 or .003", but I did mention being compulsive. The quick polish with emery is mostly  to make clear any area that needs a touch more file work. One could make a case that nothing needs to be done to the bottom three flats, except at the muzzle, as they will be hidden by wood and I am sure there is plenty of historical precedent for this, but it is just not how I want to do my work.
 I won't get into the details of draw filing too deep, working at the bench will teach you better than my explanations. I will say that I like a new file, but more important than new is good quality, that means a Nickolson, Simmonds, Sandvik, Grobet or similar. Money spent on cheap files is money wasted.
I also clean the file often with a metal bristle "toothbrush"(I like these better than file cards), and follow cleaning with chalking.
 As for polishing flats, I simply wrap emery (wet or dry) around a soft pine block cut to suitable size and the edges broke.   






« Last Edit: April 01, 2021, 12:58:36 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #13 on: October 09, 2010, 02:36:48 AM »
 Still probs with the pics!



« Last Edit: March 29, 2021, 03:39:20 AM by Ky-Flinter »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #14 on: October 09, 2010, 11:32:23 PM »
  I will brown all the hardware. This polish is at about 220 grit and I will have to re-polish before browning, because I will scuff things by handling during the build. When I brown, I am careful about cleaning and handling. I may put on 10 or more coats, generally every 12 to24 hours, and I card with a soft brass brush, I like a thick, dark, somewhat rough brown.
  The tools are what I call smooth rasps. They are flat on one side and slightly curved on the other. They cut slow and leave a finish that takes minor work with 100 grit remove the marks. I bought them about 30 years ago at Wholesale Tool in Tulsa. They are the only ones that I have ever seen.
 I am going to digress slightly from the build to tell you a little about who and what I am. I make my way as a metal working professional, specifically I am a Tooling Specialist. I am NOT a tool and die maker. I help choose, order, organize, store, maintain and preset cutting tools, tool holders and work holding. For someone to say they know ALL about tools, would be like someone saying they know ALL about long rifles, but I know fair amount about tools. I tell you this and show you pictures of some of my planes. Because in letting in the barrel I am going to show you how to make a scraper plane and its cutters. I want you to know that I have some experience to draw on; I have usually do it wrong, done it half right and finally done it right. 
 You can also see some of my hammers( I am proud of the rack for them).







« Last Edit: April 01, 2021, 01:12:14 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #15 on: October 10, 2010, 09:11:22 PM »
 I am useing a 1" barrel, but any of this can be easily adjusted for other sizes. This is a straight barrel, and that is a good choice for achunk gun and I think a good choice for a starting builder.
 The first thing that we want to do is to define the sides of the barrel in the top of the wood so that we can start removing waste from between the sides. The waste removal will be done mostly with a gouge and mallet, but defineing the sides, as final loction of the bottom flat and the two angled flats will be done with a sraper plane.
 I actually made two planes for this build, the scraper that you see and a 45 degree cutting plane. I had always wanted to make a barrel cutting plane, but after completing it I could not make it function. It is now in the "raw Material" pile. The scraper plane works great though.
 You will notice that the spacer plate is .300" thick, this is the same as the distance of the barrel to the face of the wood in our layout.
 When assembling the plane don't forget to drill for the hex head bolt (I used 3/8-16) and to counterbore for the nut. The counter bore is drilled just smaller the the distance across the nut corners and then the nut is malleted in with a little epoxy.
 The body pieces are epoxied to the spacer block. Be sparing with the epoxy as you will have to remove any sqeeze out fron the "poscket", the slot between the blocks. I did my glue up on a graite tile from the home store. The glue will dot stick well to the granite, though some times I put wax paper under a glue up for the same reason.
 We don't just want to clamp the bodies to the spacer plate, we also want to clamp the body pieces down to the tile, so that they are even, flat and square. This involves some  alteranate tightening, loosening and retightening of clamps.
 This glued assembly is srcrewed, but NOT glued to the guide plate. We don't glue on the guide plate, so that if the next gun we build needs a .400" barrel set back, we can just add a shim.
 Next time we will talk about the cutters, how they are made and how they are used.





« Last Edit: April 15, 2021, 11:58:06 PM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #16 on: October 12, 2010, 04:41:44 AM »
  The multiblade is a commercial tool by GunLine with the rubber between blades. I pulled it through my channel a couple of times at the end in the thought that it was probably ground more accurately than my hand and eye grinds
 To the blades. These are all made from 3/32 x 1" O1 tool steel. The O stands for oil hardening and it is a craftsman friendly tool steel. I always keep some O1 in material bin and recommend others do too. I keep 1/16. 3/32, and 1/8" thick and some different widths. The three cutters that we need are a sides cutter, a bottom flat cutter and a full form cutter. We start all of these by hacksawwing off a piece of steel and marking one end square with a try square and carbide tipped scribe. Sometimes blacking the material with black marker helps show the line.
 The sides of a 1" barrel is approximately .420" wide, times 1/2=.210, so a line lay-ed out .250 back from the edge provides plenty of relief. We grind or file down to this line and start working out to form the cutting "ears". The narrower they are the easier they will cut. All of the shaping on these blades is done before hardening.
 The bottom flat cutter is lay-ed out to cut .420 wide and has depth relief of greater than .500".
 A lot of my laying out is done with a dial caliper. I can hardly imagine working without one, and I don't think that there is a tool for ones shop that is a much better investment.
 For the full form cutter we did our layout by laying cut and squared piece of 1" barrel on our blank and tracing it with the scribe. On this cutter the bottom and 45s are sharp, but the sides are left "safe".
 After everything is lay-ed out, we grind up to our marks from the back of the blade to give us sharp edges. The exact angles are not important, 30-45 degrees would be fine.
 Now we are ready to harden. O1 hardens at 1475-1500 degrees, but in practice I just heat it to a nice bright yellow with a mapp gas torch, start back from the edge and work the heat up to the edge, with a vise grip handle. Then plunge it into a motor oil bath, moving it around until it is dark. Later we will temper the blades in the oven, set at 425 degrees for a half hour. I put in a picture of my oil quench safety set up. My shop is in the house basement and a metal container with a metal lid seems prudent. The can in the bottom holds the oil.
 After all this we polish the edges of the cutters and the front of the cutters with emery lay-ed on our flat granite tile. Polishing the front flat will make the cutter plenty sharp enough.
 Oh, did you notice the handy blck tape handle on the back of the cutter?








pictures upload sites
« Last Edit: April 16, 2021, 12:02:09 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #17 on: October 13, 2010, 05:56:24 AM »
 A couple of things I forgot to mention, the fourth blade with the radius is a ramrod channel blade. Also, I get my tool steel from McMaster Carr, they have a huge selection and they don't have a minimum order.
 Cutting the barrel channel with the help of the scraper plane. First we are going to start cutting the channel sides with the plane. My flats are .420", so the maximum depth of the sides cutter is .210". We don't start with the cutter at full depth, we start about .030-.060" deep and then start removing waste between the sides with a gouge. The picture with the caliper is to show how to set the cutter depth. Set the caliper for the desired depth, then lock it. Place the cutter in the pocket of the plane too deep, then push the cutter into position with the caliper, while gently but firmly pressing the outside of the blade so that it is backed into the pocket. Then tighten the lock screw snugly, but don't overtighten.
 We alternate between using the sides cutter deeper and deeper and removing waste until we get the sides .210" deep.
 Now we can start defining the bottom flat with the bottom cutter. The bottom cutter and full form cutter both have maximum depths of .500", but as they have larger comtact surfaces the adjustment increments are smaller, .010-.015". As we work down it is a good idea to check the depth of the channel. I use a depth mic since I have one, but a depth gage would work fine.
 When we have the sides and the bottom defined it is good to switch from the gouge to a straight chisel to start roughly defining the 45 degree flats and start incrementally lowering the full form cutter down into the channel. As this cutter gets close to the bottom, the adjustments should get very small, as in .005". Draw a pencil line down the bottom flat and when the full form cutter "erases" the line you are at full depth.
 In using the plane, most of the effort is directed at keeping the guide plate tight against the side of the stock, this is the critical part of creating good work with the plane. I should also note that, yes the stock has to be moved forwards and backwards in the clamps to get the plane to all of the side of the stock.





 Oh, the last picture is showing that I got tired of malleting the gouge and let my imaginary helper spell me for bit.





« Last Edit: April 16, 2021, 01:13:34 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #18 on: October 15, 2010, 04:09:44 AM »
 At this point we have about 46.5" of good barrel channel, but that last 1.5" is tricky for me. It is easy to cut away more wood than intended. I should say,before we go any further, that I finish the channel at the breech square without the breechplug in, then fit the barrel with unbent breechplug, then bend the curve of the breechplug and finish fit it.
 Back to that last 1.5", I made a special tool to do this job more accurately. The first pic shows the tool and yes it looks suspiciously like a piece of scrap 1" barrel hacksawed on a 45 degree angle and then sanded and polished till sharp.
 The second pic shows the tool in the channel turned to do the bottom flat, but it will be rotated to the other 5 flats as well.
 The third pic shows how the tool is driven; we hold the tool firmly in the channel, put a piece of wood behind it to give us a striking surface and drive it with a favorite mallet. This mallet is a Lixie with hard black and soft green heads. This hammer is about $40.00, but is
 very friendly to gun building. Our friends at MC Master Carr carry this if you want one.
 Using the tool does not go fast, you don't just drive it to the end of the channel. You alternate between driving it 1/16", cleaning the chip it has raised with a sharp chisel, rotating it, driving it 1/16", etc. As you get towards the end of the channel you have to start squaring the end of the channel. We check that the end of the channel is flat and ,square by puting transfer stain on the end of the barrel and driving it back using the same block of wood and mallet.
 Here I am going to let you in on a secret that has never left my shop before. If you look to the right of my chisels you can see it. One of the best transfer stains is a woman's lipstick. They are not as messy as the commercial products, they are cheap, they come in a convenient applicator, and they are available in any color you want (such as something similar to the final color of your stock).

   

 Don't be shy, if you have questions. 



« Last Edit: April 16, 2021, 12:10:24 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #19 on: October 17, 2010, 12:55:26 AM »
 After the barrel channel is squared, I inlet the breech plug unbent, then removed it from the barrel, bent it, reinstalled it and finish inlet it. A case could be made for bending it and inletting at one shot. I may do it that way next time, as I had a difficult time with this one. My tang is 4.5" long and the longer they get, the harder it is to do a nice job. Also as the barrel gets heavier, it is more effort to manage. One thing I want to point out is the transfer marks where the barrel end butts the channel. We want to make sure to get a transfer here before we stop the tang inlet; in other words we want to make sure that the tang does not interfere with the barrel setting firmly against the end of the channel.
 The first pic is of the tool I used to bend the tang. I am not sure if this tool started life as a fuller or as a hot chisel, but it didn't take much sanding to get it ready for this job.
 The second pic shows the tool ready to use, with the tang inverted on vise jaws and a piece of brass or copper helping reduce dings on what will be the visible surface. The bending tool can be used as a hammer or used by striking with another hammer. This is one place where the advice "Wear your safety glasses or a shield." should absolutely be heeded.
 The last pic shows the completed tang mortise. I will admit that I was not satisfied with my first inletting. glued left over stock wood into the back part of the mortise and inlet it again. By the time the gun is finished the repair will be invisible, but I want to be honest about things.
 I have never cared much for putting much (or often any) taper on parts, but this might be the right place to do that, even if it means fitting the mortise by taper scraping the mortise sides. I would love to hear other peoples comments on inletting long tangs.




 



« Last Edit: April 16, 2021, 12:45:32 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #20 on: October 17, 2010, 08:44:54 PM »
  I hope it is obvious that although I am consumed with chunking currently, that what I really want to do is demystify the build process. If a person did this same build with a 7/8 x 42" barrel, a plain general purpose Southern rifle would result. The rifle I am shooting in the pictures was built this way and it has shot offhand matches, chunk matches (I did change the sights), and took a lot of squirrels (.45 with about 20grains of powder) when I still hunted. It is also an easy build (as builds go) and one can progress to more complicated work in future builds. I hear sometimes that a beginning builder should start with a precarve and I am sure one would learn some skills, but at the same time would learn very little about the layout relationship between the components as it has already been done by someone else. I am not against precarves, but think they shine best for the guy who wants to build only one gun; wants to have a nice gun rather than learn gun building.
 I want to thank my mentor, Lee Good again for teaching me, and thank you and the other kind readers for letting me pass this to someone else. As you learn, I hope you will share with someone else.
Greg Newcomb


Ready... steady...
« Last Edit: June 08, 2011, 04:06:46 PM by Tim Crosby »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #21 on: October 19, 2010, 06:09:02 AM »
 This would be a good time to install the powder drum. The first thing to do is find and mark its location. I want the drum threads to not cut the breech plug face (please note many new and old guns have the powder drum intersecting the breech plug to varying degrees). We have to locate the breech plug face on the outside of the barrel. One way is to measure the length of the breech plug threads and transfer this measurement from the rear of the barrel. I chose to measure from the muzzle to the breech face down the bore and transfer this. I took a long (59") ramrod, hammered a pistol cartridge case onto one end to create a nice square end and put my homemade depth gage block on the other. The block is a handy thing to have, because you can take measurements as long as any dowel you create. It is just a block with a 3/8" hole drilled through it, a pinch slot sawed and a tightening screw installed. So I used this and scribed the breech face on the right flat of the barrel. My drum is 5/16-24, so I measured over .180 (.312/2=.157+.024=.180) and scribed a centerline. The .024" is just some thing between .015 and.031" that gave me a round number. Once this line is marked we cross it with a line .500 down from the top flat and there's the center of the drum. I punched this with a very sharp center punch and moved to the drill press.
 As you can see the 72" axillary table is earning its keep again. I put a small center drill in the chuck and carefully found the center punch mark and center drilled. Next I pilot drilled through to the bore; a good rule for pilot drills is for them to be the same size as the distance across the main drill's chisel point. Next I put in the tap drill and drilled through. Finally I put my tap (usually this would be a plug tap, but I had plenty of clearance in the bore to use a taper or starting tap) in the chuck. I only hand snugged the three jaw chuck on the tap, so the tap was guided, but not pushed by the chuck; I clamped a small vise grip to the tap and started turning in and backing out the tap, letting it feed itself. This is a Rayl barrel and very tough, but with oil and chip cleaning I got through.
 A couple of things; one, at this point the drum will not install to completely flush. The usual method of dealing with this is to chamfer the tapped hole till it does go flush. I chose to take a 5/16 end mill and counterbore about .060" deep. Two, the usual recommended tap drill for a 5/16-24 tapped hole is a letter I drill,.272", I used a letter G drill,.261. The .272 drill produces a 75% thread, the .261 drill produces a 100% thread. 100% threads are not noticeably stronger than 75% threads, but 100% threads do seal better.




« Last Edit: April 16, 2021, 01:03:23 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #22 on: October 21, 2010, 04:12:49 AM »
 The next step is to pin the barrel to the stock. This barrel being long, I decided to use 4 pins.
 Here is how I located the pin positions. I know that I want the front pin fairly close to the muzzle, I also know that the end of the ramrod channel is going to be 3.5" back from the muzzle (one Greg handwidth) and the front of the first thimble is going to be 4" from the muzzle. I sketch these in on my pattern and choose by eye to put the front pin 2.875 back from the muzzle. This doesn't interfer with any thing and leaves room for a nose cap if we want. I mark this on the top flat of the forestock, choosing this so that I can transfer the location to the stock side and the barrel, because we are choosing the pin locations and will mark the underlug locations from these, not the other way round.
 Next we pick by eye a spot between the front of the grip rail and the front of the lock plate. We measure the distance between the two marks, divide by 3 to get 4 locations and come up with some goofy number like 12.384". We adjust this to something sensible, in my case 12.5", and this will be our center to center distance for the pins.
 We erase the preliminary mark on the grip rail, and start measuring lengths of 12.5" from the front pin mark that we made first. I did this with a pair of trammel points, but a yard stick would work.
 After the locations are laid out, we can transfer them. For the barrel, I had the breech out, so I just turned the bottom flat 90 degrees to the side and and scribed a mark. For the stock I took a small try square and made a line on the side of the stock. Now this is important, we don't cross the lines to tell us how far down to put the pin hole. Any lines you see running parallel with the barrel are stock bottom lines. How far down the pin holes go is not determined by the stock, but determined by the barrel, and we will use this in our drill press set up to get the pin holes in the right place.
 We will get to that, but first there are the underlugs to make and install.

   




« Last Edit: April 16, 2021, 01:18:12 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #23 on: October 24, 2010, 12:21:52 AM »
 There are a lot of different commercial underlugs and different ways to make your own, here is mine. I don't know anyone else who does them this way, but wouldn't be surprised at others doing the same. My lugs are not tee shaped. they are just flat with 60 degree ends. Since they only have their thickness to generate their strength I make them a little thicker, 1/8" to be exact. I came up with these when working on a very thin rifle and wanted to set the pin high as possible and these made the depth of the dovetail in the barrel useable space.
 These lugs were made to go with 5/64(.078)" pins. They are 1/8 x 3/16. I only had 1/8 x 3/8 on hand, so I ground a small piece down on the belt sander.
 I have made a little 60 degree miter box to make it easy to cut accurate angles to match the dovetails. The dark notch across it proves room for a small c-clamp to hold the material.
 The second pic shows it in use, clamped in a bench vise. You might take note of the piece of material with the taper on one end. It is a piece of the original material, ground, case hardened, and sharpened into a mortising chisel exactly the same width as the lugs. This is handy when inletting the lugs.
 The hand vise is handy for  any file work on the lugs when fitting them to the dovetails.
 Next time we will make the dovetails.





« Last Edit: April 16, 2021, 01:22:50 AM by okieboy »
Okieboy

Offline okieboy

  • Hero Member
  • *****
  • Posts: 819
Re: Building a Chunk Gun
« Reply #24 on: October 24, 2010, 05:48:19 AM »
 Chunk drill.





« Last Edit: April 16, 2021, 01:25:15 AM by okieboy »
Okieboy