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- M 9mm SMG Individual Parts | Firearm Parts & Accessories - Gun Parts & Accessories
- MAC 11, 9MM, 380 WELDING JIG
- Frame Weld Parts
- MAC11 9mm Construction & Conversion
So whether you are making an NFA post sample, or a semi auto, this jig has you covered! The legal construction and possession of a fully automatic firearm is controlled by the B. Treasury Department. Proper application, if required, to the B. Local and State laws vary and may restrict ownership of this or similar firearms.
Possession of this template, tube, and a parts kit may constitute possession of a machine gun, EVEN if it is not assembled and the receiver is incomplete. The adapter is finished is jet black anodize and comes complete with threaded insert, allen wrench and instructions on installation.
Call for questions. If you want a side folding 6 position M4 style stock for your Cobray M 9mm Semi Auto gun, this is the set up for you! This set up includes: The adapter is a two piece design cut from the same aluminum as most AR receivers. This allows the bracket to be bolted to the gun for improved strength. Upgraded folding adapter offers upgraded machined parts, machined improved locking buffer tube slot to prevent turning, upgraded hinge spring, improved, wiggle free locking hinge, slimmer design and harder coating.
The adapter is finished in jet black anodize and comes complete with threaded insert, Allen wrench and instructions on installation. This rear stock adapter is a two piece design cut from the same aluminum as most AR receivers, machined to cradle the receiver for added strength. Upgraded folding adapter offers upgraded machined parts, machined improved locking buffer tube slot to prevent turning, upgraded hinge spring, improved locking hinge, slimmer design and harder coating. Allen wrench and instructions included. ATF approved!
It has a custom designed inner rear spring spacer that replaces the inner OEM part. This allows the bracket to be bolted to the gun for a great fit. Zero on both pieces is located at front bottom. Measurements are 'up' and 'back'. Or, height and length Pay special interest to the pin sizes, especially if experienced in making the M or M some time ago. The rear stock block retaining pin used to be a cold rolled pin inserted with some difficulty. Or, a 'C' clip in the SAP models that had the "semi-auto carraige" captivating thesear pin.
Things have changed since Gen. Mitch Warbell ruled MAC. This new pin is an improvement over the old pin, and inserts from the right side. The trigger pin stops on the outside right wall. It now has a low profile rounded head like the stock block retainer pin and it still locks with the clever locking spring wire. Chances are, the guys working on the guns got tired of fighting the trigger spring just to get the locking wire in place. It is common to forget to start the locking wire which must be in place under the trigger pin to lock it before inserting the trigger pin.
It was always remembered just after the fight to get the trigger spring and pin in place. So everything had to come out and be started again. See what you missed if your kit has the new pin? The new pin is also used in the semi-auto model, but is inserted from the left side in that gun. Some of the pins supplied are still the old design, so be familiar with the difference, as a different size hole in the right side will be necessary for the old pin. These differences are noted in the notes to the side layout templates.
It is apparent that the old style pins were either manufactured for use in either the SMG or the semi, or modified for use in the semi, as they have a locking wire relief ring on both ends. When ordering a kit, some difficulty can be relieved by specifying that the 'new trigger pin' is desired in your kit.
Unless the builder prefers the old style pin, which, having no head, is flush to the sides of a properly formed frame. It is supposed to be. This can be easily resolved. Take care to get it cleaned up all the way to the inside of the selector lever boss, which rides against the outside left surface, and keep the file parallel to the pin's surface.
Another solution is to use a letter 'L' drill, which is.
Any and all are commonly available at any professional tool supply house, or through one of the tool suppliers listed in the back of this book. Just don't be in a hurry. And, remember why machinists love Mototool! More about fitting and tuning later. If the gun to be assembled is to be a semi-auto only gun, the holes dirilled in the formed flat will differ from the SMG, selectfire models.
It is also necessary to place the hammer pin hole to the rear as shown on that drawing. Since the semi-auto unit cannot use the stock assembly, the rearmost holes can be disregarded. The same regard for the 'old and new' types of trigger pins applies to the semi and SMG models. If the flats being used are handmade, it will be necessary to put in the stock latch pin holes at the rear, if the stock is to be installed. Using '" as the nominal flat thickness, the height is.
The height of the hole is the critical dimension. This pin is nothing more than a stop for the stock latch assembly. It's proper dimension is. Deburr all holes drilled inside and out with a flat file or the Mototool and check the pins for fit and alignment of pins from hole to hole. Minor dressing of the front upper receiver connector pin holes will be done after the 'front tabs' are welded in place. It is really a waste of time until then.
M 9mm SMG Individual Parts | Firearm Parts & Accessories - Gun Parts & Accessories
Misalignment is pretty common, but is seldom excessive. The differences are obvious. This position is critical to the proper function of the gun. It is also the only area in the entire relief in the bottom for the magazine, trigger guard and trigger clearance that is critical. The face of the relief that gages the forward position of the trigger guard is the most important. If the frame has been properly formed, and the inside dimension held close, the width of the outward shoulders on the trigger guard where it is formed for the chambering ramp will effectively hold it on center to it's proper position.
MAC 11, 9MM, 380 WELDING JIG
The front face of the relief must be carefully measured, scribed and filed in place. If the face is a little wide, it is of no consequence, so long as it is kept centered, but it is still best held very close. Distances between the edge of the relief and the outsides of the frame should be frequently checked during the filing to keep them identical.
Do not cut forward of the scribe line gaging that position of the guard. If the reader buys a bent center section, as is available from suppliers, and the rear is cut off just behind the rearmost stock block mounting hole, this can be used as a template to lay out the bottom of the frame. Care must still be used however, in cutting in the triggerguard relief. First, the entire relief areas are roughed in leaving them a little small in all directions.
The trigger clearance slot can be cut to size, but left a little short. It doesn't have to be square, and can be left round if the roughing work is done on a mill. In this case, take it to size. A little over doesn't hurt. The magazine well is best left undersized and cut to size after the magazine housing is welded in place. Just make enough room to work in it. Some prefer to precisely cut it to shape and size and use a metal magazine to align the magazine housing for welding.
Experience has not proved the value of this procedure. A simple jig for welding will be explained in chapter four. Assembly will detailed in chapter 5, with a few touch-ups to improve function. It is arranged in 41 steps: Make flat 2. Drill locator holes: Form the frame channel 4. Deburr and correct rough areas 5. Drill trigger group holes 6. Weld front tabs inside frame 7. Weld sear stud in place 8. Weld sight plate in place 9. Grind weld areas clean Layout bottom area for mag well, trigger guard, and trigger relief Cut out bottom relief File in trigger guard to fit Assemble upper receiver to lower receiver with pin for primary fit Check trigger guard to barrel alignment before welding Tack weld trigger guard at frame inside bottom after removal of upper Weld trigger guard at front outside Weld trigger guard inside frame behind side tabs near chambering ramp Clamp magazine housing to frame.
Check square and alignment to center line of frame.
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- MAC 11, 9MM, 380 WELDING JIG!
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Weld behind mag well centered in mag well per sketch no. Check clearance in mag well for passage of magazine. Grind clear as necessary Assemble upper receiver to lower with pin, and adjust upper rear if necessary before welding Weld upper rear on each side top Grind upper rear welds clean Clean up weld on front of trigger guard File off any remaining burrs, and cut in the wire relief at inside left top of trigger guard, tight against the inside wall.
Prepare for metal finishing sand paper, sand blast, etc. Finsh metal Polish top of disconnector and bottom of sear catch areas Assemble trigger group and mag catch grip assembly Drill barrel retainer pin hole with barrel installed in upper receiver and install retainer pin Assemble upper receiver ass'y and install in lower receiver Check for function flaws in both modes of firing and correct problems Test fire Fear no evil!
It must be done in a particular order to avoid complications. For example, if the trigger guard and magazine well are welded into place before the trigger group holes are drilled, it is more of a hassle to hold the frame, lay out the holes, and the drilling fixture cannot be used. Most importantly however, is to remember not to weld the upper rear top welds before checking the fit of the upper receiver assembly with complete bolt assembly to the lower with the trigger guard and magazine housing welded in.
The stock assembly is relatively simple: It would be prudent to use the stock rail section in the frame, with the block in place prior to welding to be certain that the block will be centered in the frame. In the event that the rails bind, check first to see if there is free movement of the rail section of the stock without the block in place. In this case, also use the rail section to position the block during welding. It is held for welding by clamping or wedging, and after cleaning up the welds, the latch is assembled and the retainer pin placed and locked.
The stock assembly is inserted in the frame and checked for free movement, and both rail holes and stock rails are ground or filed for necessary clearance. So, there is a sequencial order that must be followed. No doubt, the over anxious will get the opportunity to re-read and re-do a lot of the preceeding instructions! Experience is what you get when you don't get what you wanted. Everyone can get what they want the first time out if they will exercise patience and follow instructions. The components of the basic lower reciever are as follows: The formed frame The front tabs The sear stud The trigger guard The magazine well After the trigger group holes are drilled and deburred, the front tabs are placed inside the frame taking care to keep the upward notches to the rear.
The original connector pin is not advised to be used because the heat of the weld may damage the spring under the locking ball in the pin. The factory method is to weld the top area of the bends of the tabs. Often, one side of the tabs will appear to angle away from the frame side. In this case, weld just the one laying flat to the side, and then with the alignment pin still in place, use a pair of vise grips to squeeze the errant side to the frame, and thus held, weld that side also. If welding at the 'U' formed front edge, weld it all as one continuous weld.
The thinness of the metal is difficult to weld with stick arc welders, even for the advanced welder. Therefore, the egde welding is only advised to the users of heliarc. If the builder is unfamiliar with sheet metal welding, a little practice on some scrap is advised prior to the actual welding of the frame. The simplest and quickest attachment is to weld the top of the tab sides only. It is not necessary to weld up the area along the front face of the frame to close the gap between the front tabs and the frame, but it makes a much nicer appearance, welded and ground clean. The sear stud is next and it is best clamped in place with a pair of vise grips taking care to keep the front of the jaw on the outside bottom clear of the stud sticking out of the hole.
Of course, once tacked, the vise grips can be removed to finish the weld. Just be certain that it is flat and square to the clean deburred hole before welding. Advise is hereby given to the wary: Occasionally, a Model 10 part may appear in the trigger group parts. All of these are obvious but. Please note that the thickness of the base, that distances the contact surface of the sear to the bolt, is thicker by. If used as is, this could prevent engagement of the sear with the bolt, resulting in a "runaway gun" phenomenon like that described earlier with the fixed full auto firing pin in the semi-auto gun.
Either chuck it up in a lathe or drill press and turn it to the proper dimensions, return it for an exchange, or trade it off at the next gun show for what you need. Now, grind the areas inside the front tabs clean for fit to the upper receiver, and the sear stud weld clean for appearance. Place the rear sight plate also called the "backing plate" in position over the area of the rear tab containing the two holes for the two pins of the bolt assembly and clamp in position with a small block of metal or wood placed inside the frame.
Clamp on this block to hold the sight plate in position, or stand the frame back end up in a vise and lay the plate down in the width allowed for it. Measure from the top of the sight plate down to the top of the frame approximately. Tack at one upper corner and the opposite bottom corner. Weld only the cut areas of the sides of this plate, carefully filling them up. Grind this weld clean and mildly radius the sides. Only in the event the stock kit will be used will any consideration for the bottom clearance of the plate be given. In all of these welds, avoid overwelding.
Experienced welders know to use weld sparingly on such thin metal.
Frame Weld Parts
Broad area coverage tends to cause a contraction that warps the metal and these distortions can change the relationship in the dimensions of parts to each other enough to create binding that is just more work to fit in. The only obvious exception here is the sight plate at the back. With all of the afore mentioned finished, place the trigger guard in the frame and check the square and center of it to the frame.
If the guard area outside the frame surrounding the trigger is out of square, it is of little concern but for appearance. Since the wide tabs of the inside position it in the width, one need only be concerned with keeping the bottom shoulders to each side and below the feed ramp flat to the bottom and properly dimensioned to the front of the frame. This position directly affects how well the gun will chamber and is the reason for all the concern in cutting the relief for the trigger guard, and the fitting of it to the barreled upper reciever.
Be certain that the barrel is tightened well into the breech block of the upper reciever housing before using it as a gauge. Be sure that the relieved areas have been thoroughly deburred, and check the stamping of the trigger guard for any residual burrs. Remove any burrs encountered.
Aside from making a sophistocated block to hold the trigger guard in place, consider a spot or two of super glue instead. The welding required will have enough intense heat to burn the glue away. It is cheaper, and it's sure faster. Use a drop at each side of the chambering ramp area and at the outside front where the trigger guard begins in front of the trigger. Thus positioned, tack weld each side at the bottom behind the trigger and inside the mag well, filling up any overcut. If the trigger guard stamping was clean and to dimension, the width of the tabs at the chambering ramp should be holding the guard on center in the frame.
Should the guard be accidentally glued out of position, a little acetone solvent super glue remover will dissolve the glue. So will a little heat, but don't use both unless you have a death wish! With the inside bottom tacked, weld the front of the guard in place across the width of the guard taking care to break clean from the edges to avoid burn out.
Then, go to the inside of the frame again and tack weld behind the tabs mounted in the gun. Fill the angled cut to each side but do not run into the area under the tabs, as that is where the stock rails must slide. With the upper receiver in place in the lower receiver, slip the connecting pin through the holes. Have before you the drawing number If resistance is encountered, bend the upper rear, first tab bend area of the frame ever so slightly to allow the pin. A small crescent wrench works well for this.
Using a nominal flat thickness of. This should be a minimum, but unless the flat is thicker than. Thus established, weld the top two sides and grind those welds clean. Clean up the area to each side at the front of the mag well behind the guard so that the magazine housing will clamp squarely to the bottom of the frame, and fit tightly to the back of the guard. The center of the front of the housing must be centered to the guard to hold the mag in proper position to feed.
This is the reason for the hassle of fitting the guard to the upper reciever barrel before welding. Be sure to place the housing with the magazine catch holding tabs away from the frame and to the rear. Ideally, the housing will be centered to the trigger guard, hich in turn, will be centered to the barrel. So, measure the outside front corners of the housing to the outside edges of the guard. That done, double check the center of the housing to the frame outside edges both at the front and the back of it, and lay a straight edge along the side of the frame on each side to be certain the mag well is in a straight parallel line to the straight edge.
If necessary, shim the housing so it is square to the frame. If this is not done, then either the weld or the grip will have to be trimmed for the required fit. Weld the front of the housing to the trigger guard at each side, down from the frame about one half inch. This is the factory method, and it is a job for experienced welders judging from how fine it is. Under no circumstances weld the outsides of the housing at the top of it to the bottom of the frame!
Such a weld will make the frame warp so badly that all of the work done will be useless. The welding advised will render a solid, clean looking unit capable of extended use and abuse. If the builder does not like the. Shown in sketch number 11, is a dandy little jig that will hold your mag housing to the frame well for easy positioning and welding. Either two pieces of metal can be drilled for passage of the bolt, or one of the metal plates can be welded to the bolt head.
A wing nut is much handier than the standard nut. The inside plate needn't be a snug fit, just long enough to span the mag well, front to back. After welding, check the housing with a magazine for clearance, and grind any necessary areas for it's proper fit. If the mag well area was intentionally left small, it is now very easily cut in now using the inside wall of the housing as a gauge to size the opening. Use light strokes in the direction the tool pulls climbing cut to remove the metal. The remaining parts to the frame are the stock kit.
It is composed of these parts: The stock block The stock latch The stock latch pin The stock latch plunger The plunger spring The stock rails The wire stock butt The stock hinge pin and clip. However, it is only the stock block that is of importance right now. It must be welded into the frame.
MAC11 9mm Construction & Conversion
Usually there is enough metal protruding that using the heliarc welding system, no metal rod is even necessary. Just wedge the block in place with a small piece of wood, and make two quick circular passes on the stems. Grind clean. Be certain that this block is the last piece welded into the frame assembly. The safety assembly was not mentioned because there is nothing to weld in that group. It will be discussed in the next chapter. All that remains now is to assemble and fit out all of the parts, and make the minor corrections. So, let's put it together for the first time! Instead of the sear stud welded into the front center hole, the bent piece of metal with it's tab protruding to the rear and right may be welded in place, or not.
It is just extra weight. The sear of the semi unit is that forked yoke thing that fits under the trigger guard 'wings' from the rear against the block that rides in the front recesses of the fork and against the back of the trigger. The hammer and it's spring are pretty obvious even to the inexperienced, and those peices pinned in, hold the sear yoke downward.
All of the components from the sear yoke to the trigger are kept in place by the tension of the rear spring. The safety goes in from the right side, and is locked in place by the locking wire, which also locks the trigger and which in the semi unit is in the right side of the gun, as the trigger pin inserts from the left, regardless whether old or new style, but be mindful of the style of pin before drilling the right side hole, just as needs to be done in the select-fire model.
The hammer pin locks with a 'C' clip on the outside of the frame, and doesn't care which side. The description given may be difficult for readers to understand. So o o o o o o, Most of the users and builders find no use for the stock kit but extra weight. In fact, they may only have it because they had to buy it to get the SMG parts they wanted. If the stock will be installed, fitting and assembly will be covered last in this chapter, along with the safety assembly, which also is usually ignored.
One small variation is detailed that could save someone's life. This is a modified cocking knob that will serve. This will be explained later. Assembly begins with the upper receiver mounted in the new lower receiver. Check first to see that the inside upper rear of the frame receives the rear of the upper receiver. Ideally, the fit should be as close on the top as both sides. Then press the upper down at the front to check the pin alignment. The connector pin should slip in and out with little more than finger pressure, and hopefully, any resistance is nothing more than a stiff locking ball in the connector pin.
If no resistance is encountered, It is just the locking ball of the connector pin. However, it may be necessary to double check the bottom to top dimension at the rear of the frame. The reason for making the top welds last next to the stock latch block is to be sure that the dimension in the sketch number 10 is correct. If there is a problem with the front connecting pin passing through the upper receiver, check first to be certain that the holes are not misaligned.
But even then, it may be a little tight. When stroking the top of the connector holes, do not exceed. It is best not to exceed. It is also possible to get a little play by lighty filing the inside top of the rear of the frame. Due to the large area here however, it is advised that very little be removed at this location. As last resort, the trigger guard wings on either side of the chambering ramp can be filed down a little. This is not an advised practice unless it becomes obvious that the guard was welded in place with the bottom shoulders not fully down against the inside bottom of the frame.
Changing the distance from the bottom of the magazine housing to the bottom of the bolt feed lips is not advised, and cutting the top of the trigger guard wings is doing just that. What will result is the bolt striking the lips of the magazine, and repairing this by. Good magazines should not be altered except in an emergency condition! If the trigger group holes were placed to print, the trigger guard was welded in properly, and the rear heighth is correct after weld, the only logical problem that could exist is the frame being warped. Sight down the bottom corners of each side or use a straight edge to determine this.
Otherwise, there should be no problem. Throughout the fitting, precision relies largely on the eyes of the builder. One useful trick in the machining industry is to white out dark metal and darken blue shiny metal. Then, using the straight edge of a mint condition machinist's scale a six inch flexible metal ruler or the edge of a precision square or rigid ruler, sight across the metal for low or high spots "humps" and "holes". In the event that the front edge of the top of the rear of the frame bends down slightly, a great deal of the fitting problem discussed so far may be eliminated by lightly filing here.
If it is flat, leave it alone and adjust from the front connector pin holes and if necessary, the guard wings. Now, assemble the trigger group parts starting with the trigger cluster. This consists of the trigger, the disconnector, the disconnector pin, the trigger spring and the trigger pin. Before assembling the trigger cluster polish the upper curved surface of the disconnector with a fine file and emery paper.
It should be a slick shiny finish. Assemble the disconnector to the trigger with the trip bar of the disconnector to the left side of the frame. The trip bar is the round pin that protrudes to one side of the disconnector. It is engaged by the trip when the trip is struck by the forward moving bolt at it's frontmost movement in the semi-automatic mode. Removal of the trip from the trigger group assembly will result in the gun functioning in the full auto only mode.
The assembly of the disconnector to the trigger is most easily accomplished using a bench vise, vise grips, or 'C' clamp to press the disconnector pin in place. It should be pressed into place since hammer tapping could break one ear of the yoke that. Place the trigger spring over the trigger, but do not attempt to lock the hooks of the trigger spring into position before the pin is in place. This pin enters from the left and it must be remembered to place the locking wire in position under it before continuing. This is a good place to cut a small relief in the weld of the left tab wing, tight against the frame wall for the wire.
It must be as deep as the diameter of the wire so that it will not interfere with the lay of the upper receiver when in place. A small triangular file or edge cutting file works well for this, but nothing is as nice as the separating disc mounted on proper mandrel for the mototool. The separating discs are Dremel part number , and come in a small, round plastic containers of three dozen.
They are very fragile and must be used with that in mind. Break a couple, and you'll get the idea! Gunsmiths love these little guys as they have a great many uses. If the reader has some experience with project building, this text is just being read now, and construction has not yet begun. So depending upon the particular welding skill of the craftsman, the weld in the left side tab wing of the trigger guard can yet be placed to leave the necessary space for the locking wire.
In the factory guns these two welds are mere dot tacks made by welders with a lot of experience. The wire must fit tightly against the inside wall, and may need to be bent from it's original shape to properly fit and lock. When all of the trigger group parts are in place, it should be tight. With the old style trigger pin, if the builder forgets the locking wire assembling the trigger, it will be necessary to disassemble all that has been done to properly place it.
In this case, the locking wire is the last thing encountered before positioning the trigger spring hooks. So, either way, get the wire in place and the pin through the trigger spring loops and trigger and pressed completely in. Remember though, that it is better to have a tight fit, so the best method of fitting holes is to use the appropriate reamer followed by a rolled up piece of or grit paper stroked in and out of the hole for a clean slide of the pin. Often, just a minor difference in the hole position can make life difficult during assembly.
At the trigger holes, with the new pin, it is a simple matter to run a drill through both holes at once to align them. If the safety assembly will be used, it should be put in before the trigger group parts are in place, as it sets directly under the sear.
Insert the spring, and then the ball, and turn the frame upside down and push the small protruding tab with the hole in it through the slot. Be certain the locking ball end of the block is to the rear of the frame. Hold it in this position and place the safety button over the tab outside the frame and press the roll pin through it, catching the tab and the assembly is complete! Of the two wire fingers extending out from the trigger spring, one has a straight length with a small bend in the end.
Using a medium sized flat tip screwdriver, push this bent tip down under the trigger. See that it locks there. The other wire is the disconnector spring section of the trigger spring. It fits under the trip bar of the disconnector. The trigger is now properly installed. Carefully wiggle the selector lever back and forth while lifting the locking wire to get the pin fully into place. Unfortunately, it must be noted that most of the trips out of ten purchased had to have the sear pin hole opened with the mototool for the pin to pass. Looking back, it is best advised that care is taken to open the hole at the top of it to minimize binding.
With this assembly completed, release the locking wire and check for tension. It should be tight. If not, it is usually easiest to bend the end over the trigger guard wing, but alas! The stock kit is a simple affair, and I'll try not to insult your intelligence with my explanation. The 'T' shaped piece with a round protrusion that is the stock latch button has a spring well in the middle of it.
Drop the spring into it, and top the spring with the stepped plug. Now, with the stock latching block welded into the frame, place this assembly in the block so the round stem drops down. Now, pressing the plug and spring down, insert the locking pin from either side and through the frame and snap the 'C' clip over the outside end. It may be necessary to tap the pin to get the head fush with the side.
All that is left is to press up on the protruding button on the bottom, and slip the stock rail into the frame with the notch up. Attach the folding butt of the stock to the rail assembly with the pin and 'C' clip , long loop up, and hey! If the button will not depress far enough for the stock rails to pass, you have the wrong spring in there. Last, it is necessary to assemble the bolt group. This group consists of the bolt, the recoil spring, guide rod, and rod pin.
It is the same pin, but the semi version has an elongated slot to allow it to move when struck by the hammer in the gun with the bolt closed on the cartridge. The full-auto 'fixed firing pin' simply has a hole in the middle that is locked by the same cross pin.
The extractor is the next important component. The extractors supplied with the kits are really not finished. They need to be. They can be filed flat first, or stoned with something like a course sharpening stone, but it should be flat. Norton, Gesswein, and Congress all have a line of stones for polishing that are excellent for this work. Enco Mfg. However, a sheet of or grit emery paper glued up on a flat board or piece of metal is quick, cheap and easy for such things as polishing out small flat surfaces.
It's still a good excuse to buy a nice assortment of polishing stones! With the sides of the extractor flat and smoothe, stone and polish the radial surface that the cartridge will strike when chambering. Then turn the extractor over and very carefully clean the area under the extractor lip, and stone or otherwise polish this area keeping the lip square. The separating disc referred to earlier is great for this, but really be careful to just touch the surface of the metal a little at a time.
If the extractor can be held in a bench vise or the like, it will likely reduce error. If the spring well is polished it will prevent the spring from dragging against the rough surface as it moves. A close look at the extractor spring will reveal that it is trumpet shaped. The small end goes in the spring well of the extractor. Installing the extractor is made easier with the aid of a small cheap 2" 'C' clamp. This is used to hold the extractor in compressed position while the retainer pin is driven or pressed in place.
This is pushed through the bolt body and the compressed extractor from the top and the clamp removed. The retainer pin is then driven through the hole from the bottom, pushing the temporary pin out as it slips into place. With the extractor and spring in place, compressed by the clamp, one should be able to see the hole in the extractor in line with the bolt body. Uusually, a light tap at the front will bring it into alignment for pinning.
The firing pin will need some consideration. If, for instance, the. The purchase of the full auto firing pin solves that problem, as it will interchange with the semi-auto firing pin and the bolt assembly will be functional in both units. Once again be warned that the full auto firing pin must be replaced with the semi-auto firing pin for use in the semi only reciever.
The firing pin in the semi kit can simply be welded in place at the back, and the weld cleaned up.