Building an AK-47 Receiver1

Collecting and Shooting the Military Surplus Rifle (2005) - Surplusrifle.com

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Article by Rob Summerhill (RapidRob) Adobe PDF Downloadable Version of Article

First off, you will need to purchase a flat (s) from a reputable company. This flat is from Tapco. The flat is in the white and includes the ejector and side rail.

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As you can see by the sticker, the metal in the flat and rails are not heat-treated. In order to allow safe functioning of the AK-47 when built, you must heat treat all heavy wear parts. There are several companies manufacturing the frame jig. It’s up to you and your budget as to whose make you wish to purchase. In this article, I’m more concerned in showing the proper technique to bend a flat that will function with little or no fitting required. It is important that you realize that you will be working with extreme hydraulic pressures and open flames. Take your time and make sure you are always safe while working and in fire prevention.

First off, make sure you have all parts. The main frame flat, one ejector plate and one bolt guide plate. If the stampings have any burrs on the holes, now is the time to sand or file the steel smooth.


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Here are some of the basic hand tools you will need to do the final bending of the top rails. A good, large, hard plastic mallet, a one pound ball peen hammer, a piece of steel plate to level the top rails evenly, a smaller ball peen hammer to “round-out” the bottom selector hole if need be, and a device to help get the top rail steel to bend with out leaving dimples or gouges in the steel. I’m using a modified steel chisel from Harbor Freight.

As you can see in the photo, the chisel’s edge is too sharp to be of any use to us. I ground down the sharp edge and rounded it out to allow a good surface to start the top rails to bend over 90 degrees.


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Here is the inner die of my frame bender. I have taken off the bottom rail that has two precision set pins to align the frame flat centered on the bender to align all support pinholes to match from the left to right hand side of the receiver.

This is one of the two pins that will prevent any movement of the flat while bending.


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In this photo you can see the oval hole, which will allow the two dimples on the flat a place to go while the frame sides are being bent. The rectangle in the upper die piece is for the bent on the frame’s magazine well. Both of these holes will be an indicator to you as to how to place the frame flat onto the jig for bending.

Here is a clearer photo of the rough placement of the frame flat in conjunction with jig’s frame with relief holes.


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Here I have removed the bottom rail of the jig bender, inverted it so the pins are facing upward, and have laid the frame flat onto the two alignment pins. Notice that the magazine well bent will fit into the female hole during bending.

The bottom frame with the two alignment pins is now bolted to the underside of the jig body. The screws are tightened from the center outward to “flatten” out any small wrinkles. Remember, we are trying to bend a steel plate, at the same time making sure that all pinholes will align when we are done.


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It is of utmost importance that BOTH sides of the frame flat stick out evenly. Failure to do this step will result in a ruined receiver. Use whatever you have on hand to measure the distance from the same point on each side of the frame flat overhang. Here I’m using a depth gauge.

Here a dial caliper…


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And, here a digital caliper. Use what ever you like, but make sure you check the centering with something!

To avoid scratches and gouges in the frame flats’ sidewalls during bending, you will need to lube the steel. Any good automotive grease can be used; I prefer the White Lithium type. While the Molybdenumdisulfide will work just fine, it will, however, be a bear to clean off the bent steel.


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As you can see, a good layer of grease is needed. Don’t go overboard on the grease. Too much will cause dents during bending; too little deep scratches.

Make sure to clean the inside of the jigs’ main support frame and also give it a good layer of grease.


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Your now ready to place the jig with the attached frame flat into the main support frame. The main support frame may have a letter designating the front ( F ) and the back ( B ) to help you align the jig body into the main frame. Since the AK-47 frame is bent at a slight angle, it is important that you do not get the two ends reversed, hence the markings.


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The jig is now centered on the main support frame, with the same air gap on both sides to allow a smooth bend without marring the steel plate of the frame flat. Take your time and do it right the first time. You’ll be happy with the results later on.


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There are several types of hydraulic shop presses you can purchase. This one is from Harbor Freight and was bought on sale for $100.00. There are far better and worse out there. Buyers beware!


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This model is rated at twelve tons of pressure. You can make due with far less. However, I would not try less than a two-ton press and I do not recommend an arbor press or a vise. The needed pressure needs to be smooth and controllable by you, the operator, at all times.


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Make sure your ram plate is level and moving smoothly. It is very important that you have the jig assembly properly supported underneath at all times. No wobble of the jig assembly is permitted during the pressing of the frame flat. I have added a small steel plate to prevent damage to the jig.


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Double check that the inner jig assembly is centered in the main jig frame.

Here we go. I have brought the shop press’s arbor down and have started to slowly add


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pressure. Once the steel starts to bend, stop and move the press’s arbor assembly to another point on the frame flat jig. Remember that the frame is bent at an angle. Take your time and do it right and slowly. You can “ feel “ the plate bending under the hydraulic pressure of the press. After a few seconds, you will understand what I mean. Take you time!

The frame continues to bend in a controlled manner. Soon my scrap plate will be too wide to use. I’ll use a smaller one for the rest of the “bend“.


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Here is the maximum pressure you will need to produce with the press. You have just bent a 1 mm steel plate at a 90-degree angle. At this time, you may hear a loud pop. Don’t let this scare you, as this is normal. Continue to drive the frame further into the jig. Take your time!


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Remember that you are bending the frame flat at a slight angle. MOVE the press around on the top of the jig to allow a smooth even bend of both ends of the frame flat.

Just as you get close to bottoming out on the two inside welded plates, which are marked “F” and “B” and are welded at different heights in the main jig frame, you will feel the press start to build up pressure. STOP! If you don’t you will damage the main jig frame. Move to the other end of the jig and make sure it too is bottomed out in the jig’s main frame. Is this cool or what? At this time, make sure you have the same amount of steel showing at the top of the jig as both sides need to be equal.


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Here is a view from the end.


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Same view, a little lighter to show more detail. So far so good! You’re almost there.

O.K, we now start to bend the top rails over toward the center of the frame. I was not able to show and photograph at the same time, sorry. Take your time and use the special tool to start the rails to bend inward. Once the steel starts to bend, grab your large plastic mallet and continue the bending. Use a hammer swing that will allow you to PULL the hammer towards the center of the jig just as the head of the hammer strikes the steel. This is called “ rolling “ the edge over. You can use a steel ball peen hammer to do this step. You will leave hammer marks in the metal though.


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Here, I have bent over one side of the top rail. I took my time and hammered the rail as flat as I could without leaving “ high” spots.


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Both rails are now bent over 90 degrees. I have followed up with a steel plate being laid on the top two rails and being struck with a one-pound ball peen hammer making both rails flat, smooth and even. Once again, take your time and do it right.

Here is another view of the finished top rails.


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We now have to remove the bent frame and inner jig assembly from the main jig frame. The whole assembly is up side down for this shot. You can see the two uneven welded plates that control the slight taper to the AK-47’s frame.

I have supported the upside down jig assembly on two large pieces of angle iron to allow the free movement of the inner jig for removal. There will be padding under the frame to prevent damage to the receiver during the fall.


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The inner bending jig with AK-47 receiver (no longer a flat!) still attached.

The bottom jig rail is removed. Notice the frame cut outs and the magazine well bent.

Since the inner most portion of the frame-bending jig is now held firmly by the two outer jig frame members with the milled dimples and holes, all screws will need to be removed to release tension.


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The center portion will drop free with a little help from a plastic mallet. Don’t let any jig parts hit the floor!

And there you have it, one each AK-47 receiver, waiting to be flame hardened and rivets or screws added to complete the build. Both ejector and bolt guide will be hardened and riveted or welded in place. (a later step-by-step project). I hope you have found this information helpful for your next build NEXT- Part Two “ Heat Treating the Parts “


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Article by Rob Summerhill (RapidRob) Adobe PDF Downloadable Version of Article


7/12/2005

Building an AK-47 Receiver1

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