Page 1 of 7 123 ... LastLast
Results 1 to 10 of 70

Thread: The saga of the home-made H&P Conversion!

  1. #1
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas

    The saga of the home-made H&P Conversion!

    So. Yesterday I began the saga of trying to make an federal contract H&P Conversion of an M1840. The M1840 conversion is an enticing candidate because the M1840 is nearly identical to the M1842. I would have preferred to make an M1816 conversion, since they seem to have been more common, but no one makes a very accurate M1816 reproduction musket today. Pedersoli makes one, but the word is that they basically modified their 1777 Charleville to look sort of like an M1816, but it is not a very accurate reproduction of it. So it is unlikely that if it had to pass N-SSA approval muster today that it would.

    But Chiappa / Armi Sport makes a very acceptable reproduction of the M1842, so my hope is to use it as a starting point for "retrograding" it to an M1840.

    So, a little bit of history of the H&P conversions. This document is dated and is said to make some broad generalizations that have since been refined since this article was written, but this is a good summary of the H&P conversions:

    http://americansocietyofarmscollecto...33_Altemus.pdf

    Basically, at the start of the American Civil War, both sides were unprepared. There was an acute shortage of weapons. The weapons stored in the federal arsenals included many flintlock smoothbore arms, including M1816, M1822, and M1835/1840 muskets. H&P had a federal contract (and a state contract for the state of New Jersey) to convert these firearms to rifled percussion arms. The New Jersey arms can be easily identified by the clean-out screw on the bolster. All of them were rifled. The federal contract arms, which numbered just over 12,000, were intended to be rifled, and so were equipped with rear sights. But due to the pressing need for arms, they were sent out still as smoothbores. Hence the high desirability of such arms in N-SSA comptition - with our carefully-tuned target loads a rear sight is considered by many to be a valuable asset.

    The way the H&P conversion worked was to cut off the breech end of the flintlock barrel, and then thread a newly-made percussion breech in its place. Some of the flintlocks had already been converted to percussion using the "cone in barrel" method, and these too were re-converted to the new bolster breech. So some of the arms had more of the breech end of the barrel cut off than others. But the effect is the same - the breech end of the barrel was cut off, and a new breech screwed into place.

    The H&P breech contained a chamber that was smaller in diameter than the .69 bore of the barrel. This meant a special cleaning rod was required to adequately clean the chamber.

    For my project, the idea is to keep the number of custom modifications required to a minimum.

    To this end, for the breech, what I am going to do is create a 3D model using Computer Aided Design (CAD) software. This new breech will be dimensionally identical to the Armi Sport breech, internally and externally, with the exception of the bolster geometry. This will be shaped above the stock to look more like the H&P bolster, and will be shaped below the stock so that there is additional material required to fit into the notch on the M1840 lock plate. By maintaining the same internal geometry as the Armi Sport breech, the new breech will not have the deficiency of the original H&P breech with the reduced chamber diameter. This will make cleaning as easy as it is on the 1842. By maintaining the same external geometry as the Armi Sport breech, the entire barrel assembly should drop back into the Armi Sport stock without problems.

    For the lock, my plan is to make a 3D model of an original M1840 lock plate, and then modify it as needed so that it directly accepts the Armi Sport 1842 lock internals. Most of the internals, except the mainspring, are very close to the original components already, so this should not be difficult. In fact, test fitting indicates that the bridle, tumbler, and sear all fit the original lock plate, right down to the screw threads.

    I was able to obtain an original M1840 lock plate that had already been used in a cone-in-barrel conversion, complements of Lodgewood Manufacturing. While I wait for them to get a new batch of Armisport 1842s in, I decided to start working on the lock plate:







    Right now I am modeling the original plate exactly. After I get it done, I will start modifying it to accept the Armi Sport 1842 internals. As I mentioned previously, I already did a check fit using my Armi Sport 1842 I already own, and most of the lock internals are drop-in replacements. The bridle and sear fit. The hammer hole will need to be enlarge slightly. The biggest change will be to reposition the holes for the mainspring as the Armi Sport spring is slightly different from the original.

    Then I will 3D print for a fit check.

    Sadly, it does not appear that there is enough wood in the Armi Sport 1842 stock to do the trick. There is enough wood for the mortise to work, but there is not enough wood to make the full "picture frame" on the escutcheon on the sides of the stock to fully frame the lock in wood.

    I believe I am going to try and cut way a portion of the stock at the end of the lock opening, machining a flat chunk out of it with a router, and then splice in an "extension" of walnut to the back of the mortise hole, which can then be re-shaped. The alternative is a Dunlap stock, but this will be much more expensive and probably require more work.

    I will post updates as they happen.

    Steve

  2. #2
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas
    So I uploaded my 3D model to Protolabs for a quote. I love this site as you can send up your CAD data and get a quote in an hour.

    A bit pricier than I thought it would be. Fortunately The Rifle Shop carries M1840 lock plate castings for $20. So I have one of those on order and it's waiting for me at the post office. I think for $425 I can do some file and drill and tap work.



    Steve

  3. #3
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas
    Option 2: Casting of lockplate from The Rifle Shoppe for $18:




    Not much cleanup here from the looks of things. In fact with careful polishing it might be possible to leave the plugged holes "plugged" so they look plugged but are actually cast closed.

    Steve

  4. #4
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas

    Gunsmithing 101. Or, how Steve screws up perfectly good gun parts!

    The goal here is to try and convert an Armisport M1842 to an H&P M1840 conversion. The idea is to use an AS 1842 as a donor gun. For the lock, we will want to use all the AS 1842 lock parts except the lock plate. Here is what we have to work with:

    Original lock:


    Armisport 1842 lock:


    So today I spent some time screwing up, I mean working on, the M1840 lock plate casting I got from The Rifle Shoppe.

    The casting if fantastic. It is so fine, that it has picked up the stamping details so well that I don't think the lock needs to be (or can be ) re-stamped. You'd have to remove considerable material to grind away the existing stampings.

    Also, the casting detail has picked up all the "plugged" holes from the flintlock conversion, so that I don't think I need to drill and plug them to make it look right. Alas, I was not paying attention and drilled one of the holes not-to-be-drilled, so I'll have to plug it.

    So, to start with, I did some light filing to remove a few casting flashes. Then I went straight to 500 grit sandpaper using a palm sander. I used my buffing wheel a couple of times but the grit in my wheel is too aggressive - the sand paper works better.

    Here is how it cleaned up. I was planning on doing some more polishing, but figured I better get the holes drilled before I obliterate where they are supposed to go:



  5. #5
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas
    Then I went to Harbor Freight and bought myself one of those mega drill bit packs with every bit you could imagine, and a set of metric and SAE taps and dies. Lesson one: Avoid HF taps.

    I did some checking on the threaded holes in the Armisport 1842 lock. All of the threaded holes are #10-24 UNC, except for the mainspring screw hole, which is M4x.7.

    So I started drilling holes. Here you can see my first screw-up. Somehow I got "1/4-20" in my head, so I started drilling with a .201 drill bit, which is what you need to tap 1/4-20 UNC. I realized my mistake as soon as it started drilling full-size, so I quit and re-drilled with the correct #25 needed for #10-24. However, in my haste, I drilled out one of the flintlock holes that is not needed for the conversion. So, I will plug and peen the hole, as on the originals. So my little over-drilling will make a nice counter-bore for the excess rivet head to fill.

    My first real problem came when I started trying to tap the #10-24 UNC holes. The Harbor Freight tap was crap - not enough taper so I could not get it to bite into the hole to start cutting. Here you can see I chewed up the hole pretty good trying to get it to work:



    Then I remembered I had some taps tucked away in my storage cabinet. Went and pulled them out and discovered I had 2 USA-made #10-24 taps. Good thing I had two of them, as my next screw-up was breaking off the tap in the rear-most lock screw hole.

    So I used my last #10-24 tap and tapped all the rest of the needed holes. It was then that I made my next screw-up.

    I had assumed (dumb me) that the holes marked in the casting were correct. But of course before the M1842 they were all hand made. Turns out the front-most lock screw hole is not in the same place as it is on the original M1840 lock I am working with, nor is it the same as the Armisport 1842 lock plate which is what we really want! Unfortunately the hole is close enough to where it is supposed to be that I cannot just plug it and drill a new one. It might be possible to weld it, but I'm probably just going to get another lock plate from The Rifle Shoppe.

    Next I matched the mainspring holes on the Armisport 1842 to the new M1840 lock plate, and drilled them, and tapped the top one to M4x.7 as needed.

    Finally, I was able to fit all of the Armisport M1842 lock components into the new lock plate:



    So, in spite of numerous screw-ups, I was able to prototype the H&P M1840 conversion lock, mapping all the Armisport M1842 parts over to the new lock plate, and the lock functions. Everything is exactly where it was on the Armisport lock in relation to the hammer axis, which is in the same place on the M1840, so I expect the lock to work and strike the nipple where it currently is on the Armisport 42.

    The upshot of this is that if you have a donor Armisport 1842 to work with, for $20 and a day of elbow grease you can make an H&P M1840 conversion lock. This means a big part of the project is demonstrated as feasible.

    Now for the next challenge. Not enough wood on the Armisport 1842 stock.

    This is what we have to work with:

  6. #6
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas
    Unfortunately, while it looks like we can make it work with the existing mortise, and cutting out a little more for the tail of the lock, there is not enough wood in the stock to finish the "picture frame" around the lock:



    As you can see, there are some slight gaps, which we could probably live with (especially if we made a custom lock plate, which we could then enlarge a hair to fill the hole), but the show-stopper is there is not enough wood to continue the "picture frame" to follow the profile of the tail of the lock.

    You can see here what it should look like:



    I really don't want to have to resort to a Dunlap stock. It's expensive, and they say takes about 20 hours of work to finish it.

    So. I think what I will end up doing is milling away the tail of the escutcheon on both sides of the stock, and splicing in a new piece of walnut, and then filing and mortising to match. This will allow me to fill the gaps shown above also.

    I'm not happy about this, but it is what it is.

    Anyway, I'm reasonably happy with the progress so far. So far, the project looks feasible. The real bear, coming up, is the new breech. Machining looks to be more expensive than I thought, though I have some other options to explore there. But it may be possible to 3D print a master and have it cast, too, like the lock plate.

    More later...

    Steve

  7. #7
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas
    Aaaand of course I call The Rifle Shoppe back today and they are out of more lock plates - 8 weeks minimum until new ones are available.

    Steve

  8. #8
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas

    Now you see it, now you don't! Or, how medieval armour making skills save the day.

    So, despairing over the 8-week or more wait for The Rifle Shoppe to make more lock plates, I decided to really, seriously try to salvage this one I have.

    The most pressing issue is the hole I drilled in the wrong place. I drilled where the hole was on the original casting, and that is not where I needed it to be! So, the first order of business was to make the old hole go away. In a past hobby life, I was big into making medieval armour. So one thing I can do is peen a rivet. And I can make hidden rivets. So, that is what I did.

    First, I took a piece of nail, and I rolled it between two files to rough it up, "knurling" it. I did not want it to spin while drilling or tapping the new hole, which will partially intrude on this pin:



    Before pressing it into place, I counter-sunk each side of the hole, so that when I peened a rivet head it would have a place to flow and disappear into the lock body:



  9. #9
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas
    Next I used a socket to support the lock plate and give the pin a place to go, and used my vice to press the pin through the lock:




    Next, I trimmed the pin, leaving some material to form a rivet head:



  10. #10
    Join Date
    Jan 2009
    Location
    Huntsville
    Posts
    2,571
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas
    Next up, I peened the rivet using a hammer and anvil. Old friends, they are:



Similar Threads

  1. SB Shooter looking for home
    By Jim Wimbish, 10395 in forum Base of tower
    Replies: 0
    Last Post: 05-06-2015, 11:46 PM
  2. Carbine Shooters looking for a home!
    By rich.j.ryan in forum Base of tower
    Replies: 4
    Last Post: 10-06-2014, 12:32 PM
  3. SB Shooter needs a home
    By K. Herrick in forum Base of tower
    Replies: 4
    Last Post: 09-25-2013, 11:09 PM
  4. Rich is home
    By Jan Cross 10440 in forum Base of tower
    Replies: 2
    Last Post: 06-22-2012, 06:36 PM
  5. Need a home
    By Sam Sellaro, 12403 in forum Base of tower
    Replies: 0
    Last Post: 09-29-2011, 11:36 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •