The standing breech starts as a chunk of mild steel that is 3cm x 5cmx 12cm( 1.18”x 2”x 5”) and weighs 1,4kilos(3lb). The finished breech weighs 71 grams(2.5oz). Like with the breech plug, the main challenge was figuring out the rigth sequence of steps when working such a heavy blank with hobby machines. I drew the standing breech in Qcad which was a big help getting all the details correct so the breech fits the plug I made.
Mill the blank to a perfect rectangle. Do not at this stage cut it into a “angel iron” shape
Paint the front face with dykem and mark where the square hole for the breech plug hook is going to be using the Qcad measurements. The front face of the blank is going to be several inches above the vice jaws when machining this hole. Therefore, you need the rigidity of the whole blank when doing this. Use the end of a 3mm drill (1/8”) drill to locate the corners. Center drill and drill out to a depth of 10mm.
Repeat round whole the square hole. I also drilled out the center of the hole which proved later to be unnecessary.
Use the end of a 3mm drill to locate the corner holes and a 3mm endmill to mill out the vertical sides to a depth of 10mm. Repeat for the horizontal sides using the middle hole to locate the end mill.
Don’t bother milling out the center of the hole.
Mount the blank in the vice on it sides, draw the “angle iron” on the blank making sure the long leg connects with the top of the front face (short leg). Drill and saw out.
Mill the legs on the sawn surfaces down to 8mm thickness. This will open the square hole.
The square hole fits perfectly the hook on the plug but lacks the “barb” to retain the hook.
Next step is to make the barb. Mill a square rectangle that fits tightly between the vertical sides of the hole. The corners of the hole are made with a 3mm drill and have therefore a 1.5mm radii.
To make the block go all the way down into the hole I milled a 1.5mm radii on two of the corners with a corner mill.
The blank was then soft soldered to a holding block with the rounded corners down and reduced to 4mm thickness and 45 degrees angel at one end.
The blank was heated, removed from the holding block and the solder wiped down but not cleaned off. The blank was cut down and filed precisely to fit on the hook.
Mount the plug with the barb in the standing breech blank and drill a 1.5mm (1/16”) hole that’s 2mm from the edge and goes through the standing breech and 3mm into the barb. This hole does not penetrate the barb.
Chuck a finishing nail in the lathe and file it down to a 1.5mm pin.
Remove the plug and look at the barb. It’s only got solder on the sides that will be touching the standing breech. There is no solder on the sides that will be touching the hook. Flux the barb and the square hole. Pin the barb in place and reheat. The pin will keep the barb in place when the solder flows. Sorry, forgot to take pictures of this. Soldering the barb in place gives tight fit with no slop. I can’t get the same pression by chiseling the hole for the hook.
Next step is to round the bottom of the plug hook so you can mount it in the standing breech.
The red arrow points the pin, which will be invisible in the finished standing breech.
Now we are going to carve out the inside of the shield. Paint the standing breech with dykem and trace outline of the plug. Place in the mill vice and locate the middle of the shield on the edge of the face.
The inside of the shield is going to start as a 12 mm half cylinder with a rounded bottom.
Start hogging out the waste with a 12mm endmill followed by 10mm bullnosed mill.
Finish the hogging with a 12mm bullnosed mill. The step with the 10mm bullnose significantly reduces the stress on the mill.
The inner wall of the finished shield is not a straight cylinder but a slightly sloping cone that increases in slope towards the rear of the standing breech. This sloping is done with a 12mm diamond ballburr in a drill. You can get these cheap from China on eBay.
Now comes the hard part. The bottom/edge of the breech plug is a flat straight surface that the rounded bottom of the shield must blend into. Look where the red arrow points. I mounted the plug and standing breech in the mill and carefully flatten this area with a 2mm end mill.
This left a small step in the bottom of standing breech that I removed with small stones in Dremel. This worked but left a finish I’m not too happy with.
Mill the part of the standing breech that’s below the shield level with the plug edge
Mount the long “leg” in the vice and mill down to the tang on the side of the percussion plug.
Mount the “face” in the vice slanting with 45-degree angle blocks, mill the slanted side of the face. Leave it a hair to large.
Mount the long “leg” in the vice and mill out the other side of the tang.
File out the outside of the shield and mill/ file all the sides of the standing breech face flush with the plug. Mill a 2-degree slant on the top of the tang. Sorry forgot to take pictures of the process.¨
Pictures of the finished standing breech.
Question.The tang is not finished. I need to file a thumbnail on the end, put I’m unsure how long the tang should be. I’m planning to use the plug+ standing breech along with one of my locks on a Fleeger style rifle. This is a picture of the tang of the rifle that’s my main inspiration.
How long should the tang be?
Here is a link to making the breech plug:
https://americanlongrifles.org/forum/index.php?topic=81052.msg797102#msg797102Best regards
Rolf
