■ his gun was designed to incorpo-I rate magazines built originally for I use in the British "Sten" gun. I These are readily available, cheap, ^¡^ and, most importantly, sturdy. These are presently advertised at $3 new and $2 used, which is less than it would cost to wind the spring. Purchasers of new magazines are given a choice of a "blue" finish, which means they are painted black, or a "parkerized" finish, which means they are painted gray. Even so, they represent a bargain. I suggest you obtain a few extra.
It was my intention when I started this book to give a brief description of these magazines and let it go at that. Recycling material printed in another book is similar to selling the same thing twice, a practice that should be frowned upon. However, just recently members of Congress have introduced legislation connected to their so-called "Crime Bill" that would actually ban the sale or possession of high-capacity magazines such as these. Therefore, I believe it is desirable that the material published in Vol. I be reused here. If you think you are getting shortchanged, please forgive me.
To make a magazine of approximately the dimensions and capacity as the Sten, a piece of 20- or 21-gauge sheet steel, 5 inches wide and 10 inches long will be needed. The 20-gauge material is .036 inch thick while the 21-gauge measures .031 inch in thickness. If the double thickness is used in the upper portion, an additional section, 3 inches by 3 1/2 inches, will be required, as well as a piece 1 1/4 by 1 5/8 inches for the bottom cap, or floorplate. Obtain this material with a cold finish (bright metal) if possible because it is far easier to polish for final finishing than the black "hot-rolled" material.
A female forming die should be made with a U-shaped, flat-bottomed cross section formed by bolting, riveting, or welding two lengths of 1/2-inch, or thicker, steel to a center section of the same material that is cut to a width of .835 inches. The sides should be 1 1/2 inches high, measured from the inside bottom section. The length should be at least 12 inches. Slightly bevel or chamfer the inner edges of the top walls, and pol ish them as smooth as possible. This will permit the sheet metal being formed to enter the die with as little friction as possible. If only a few magazines will be made, angle iron can be used to make this forming die, provided that another piece is welded across each end to prevent it from spreading open.
A male die must be made to fit exactly the opening in the female die—less double the thickness of the material being formed plus another .005 to .010 inches for clearance. This simply means that if the opening in the female die is .835 inch and you are using 20-gauge sheet metal, you add .036 inch plus .036 inch plus .005 inch
(or whatever clcarancc you deem proper), which totals .077 inch. This figure, when subtracted from .835 inch , leaves .758 inch. Therefore, the male die should be .758 inch wide. A double thickness of .072 inch is also subtracted from the 1.500 inches depth, resulting in an overall depth of 1.428 inches.
Cut a longitudinal slot, 5/16 inch wide and 1/4 inch deep, in the top or back side of this male die. It should have a round, radiused bottom. This can be cut with a ball-ended milling cutter or round files. In addition, all four comers should be slightly rounded.
Insert the male die inside the female die with a shim of sheet metal on each side. These shims should be the same thickness as the magazine material to keep the male die centered. Then drill a 3/8-inch hole at each end, close enough to the ends to allow room for the 10-inch magazine to be formed between them. The holes should be drilled through both the female and male dies simultaneously, while they are together. A close-fitting guide pin should be used in each of these holes to keep the dies in line while the magazine is being formed. If the dies are to be used a number of times, you should press a slightly oveisized pin into each end of the female die and ream the holes in the male die to slip-fit over them. If you only plan to use the dies a few times, floating pins will suffice.
After applying a light coat of grease, center the sheet-metal blank across the top of the female die. Put the male die, also lightly lubricated, in place on top of the sheet metal blank, and squeeze the entire assembly together either in a press or large vise. You can also force it together by wrapping a chain around the dies and another bar of metal, leaving enough space between for a hydraulic jack. The jack will force the dies together, forming the sheet metal into the shape of the magazine. Either method will form the front and both sides of the magazine body.
Now, you must form the back side. After placing a bar of steel along the side of the sheet metal protruding from the top of the die, tap it with a hammer, bending it in toward the middle. Do this on both sides. Then form a 3/16-inch ridge lengthwise on a flat steel bar by grinding a 3/16-inch-diameter rod to half thickness. Braze or rivet this rod to the plate. To complete the outside form, place the plate, with rod attached, over the top of the die and press them together. Then remove the formed magazine body from the female die and push the male die out from one end. The seam should be soldered, brazed, or riveted together, after which the lips should be cut to shape and bent inward, as shown.
The reinforcing section is made in the same manner, except that it only has three sides, with the front left open. When formed to the proper shape, with the lips cut to shape and bent inward, it is placed over the magazine body and welded or silver-soldered in place.
The edges at the bottom sides must be flared at right angles, outward from the magazine body, leaving a 1/16-inch lip projecting from each side. The bottom plate will slide onto these lips. This can be done with a hammer and a flat bar of steel, but the male die should be placed back inside the magazine while these are formed to prevent it from being bent out of shape. Clamp a flat plate to the side, flush with the bottom of the angle. Holding the flat bar against the bottom, make the bend while tapping it with a hammer.
The bottom plate is made to the dimensions shown (it should just slip over the flanges at the bottom of the magazine) by bending to shape or forming in a small die. After it is shaped, drill a 3/16-inch hole somewhere close to the center and make a marching keeper by drilling a corresponding hole through a strip of sheet metal that is sized to fit inside the magazine body. A short locating pin is silver-soldered in the hole in the keeper.
The purpose for this is for the end of the magazine spring to exert pressure against this keeper, pressing it firmly against the bottom plate, with the stud engaging the hole in the bottom plate, thus preventing removal of the bottom plate unless the stud is pushed inward.
The magazine follower can be made from 1/2-inch flat stock, by filing and grinding a proper bevel as shown, and by welding a leg of 12-gauge flat stock at both front and rear to prevent canting and resultant binding.
In most cases, factory-made magazine fol lowers are stamped or drawn to shape. This requires rather complicated, complex shaped dies. So, unless a large number of magazines are to be made, I recommend the welded-up follower shown.
A fairly crude but usable spring can be wound using a mandrel that is made using a 12- by 14-inch length of 3/8- by 1-inch flat stock. Start by grinding both the front and rear edges to a radius, or half round. Drill a .065-inch hole near one end. Then, with one end of a length of .065-inch music wire fastened in the hole, feed the remainder through a groove filed in a 1/2-inch square bar some 10 inches long. A usable spring should result by winding the bar repeatedly around the mandrel. Note: I said a usable spring. It may not be particularly pretty. Somewhere between 5 and 6 feet of wire will be required to wind such a spring. If music wire or spring stock is not available, you will have to straighten and rewind a screen door spring or similar spring. This will not be easy, but it can be done if nothing else is available.
Ti - - ■ -
SLOT FOR MAGAZINE LATCH
SLOT FOR MAGAZINE LATCH
CAP LOCK (RETAINER)
CAP LOCK (RETAINER)
3/8" GUIDE PINS
3/8" GUIDE PINS
LENGTH SUFFICIENT TO ACCEPT MAGAZINE BODY BLANK
DIMENSIONS WILL VARY ACCORDING TO THICKNESS OF MATERIAL, ETC.
Magazine forming dies.
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