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-   -   Virgin Build AK-47 Yugoslavian M70AB2 Stamped Receiver Yugo M70 AB2 (http://www.calguns.net/calgunforum/showthread.php?t=193742)

fredieusa 06-13-2009 9:20 AM

Virgin Build AK-47 Yugoslavian M70AB2 Stamped Receiver Yugo M70 AB2
 
*****Fixing/Building/putting together your own guns can/may cause serious harm, up-to and including death! That is a good reason why professional/qualified gunsmiths exist, make use of them. Also know all your laws, its amazingly easy to get into trouble with the CADOJ or even the BATFE. This thread of mine is for pure educational purposes. It is not my intention in anyway to get you to follow.*****

Virgin Kit = Parts that have never been assembled into a working firearm.

Here is a build for a Yugo Under-folder VIRGIN kit. For this build I have used a stamped/bent flat receiver. This rifle will be CA compliant, Detachable magazine capacity removed, fixed stock pinned open OR muzzle device attached so the OOL is 30" or greater.

For illustration purposes and the fact that I often forgot to take pictures, I will be using picture from other builds.

Features and regulations specific for California are NOT mentioned/listed, as i go along because it is also meant for some folks from other states.

Prerequisite: Meant for folks that have already completed a build or two from a de-milled kit. Have good mechanical skills, tools and pertaining knowledge.

I will be skipping over all (or most of) steps that one would go through (building and refinishing) while completing/building a de-milled kit. This means we will not be touching on Magazine fitting, mag catch and trigger guard riviting. Trunion fitting and rivitings, Painting/bluing or finishing the rifle (wood or metal). I have kept this build as simple as I possibly could, without the use of a mill or lathe!:)

This is the kit I will be completing... Bought back-in-the-day and it included the barrel, rivits and all.. everything but the receiver.

http://i280.photobucket.com/albums/k...2/100_0103.jpg

This kit will look like this when done.. I got the below photo from here http://akpartskits.com/cart/index.ph...&products_id=6 (not plugging them, I have no idea who they are, just used their photo so I thought I should list them..)
AGAIN this photo BELOW is NOT mine. Its from this web site. Yes the kit comes with FA parts that YOU/I discard/resell on GB.


http://i280.photobucket.com/albums/k...2/100_0100.jpg

fredieusa 06-13-2009 10:12 AM

Receiver and Trunions

Crimping/crushing rivits is the same as in the demilled kit so I will run over this fast.

Here the trunion holes were slightly small (for AKbuilder rivits) so I ran a drill through them.
http://i280.photobucket.com/albums/k...2/100_0201.jpg

Now install the trunions in the bent receiver and line holes up. For a Yugo M70AB2 you will have to drill an additional hole in the bulge of the trunion. Most receivers have the hole drilled so just center punch and drill away.

Here the receiver is almost complete with all rivits and trunions, including the Mag release/trigger guard and the pistol grip nut.
This came out pretty squared-up and decent.

http://i280.photobucket.com/albums/k...2/100_0202.jpghttp://i280.photobucket.com/albums/k...2/100_0203.jpg

http://i280.photobucket.com/albums/k...2/100_0204.jpg

fredieusa 06-13-2009 10:30 AM

Installing a "bullet guide".

If your trunion already has a bullet guide installed, you may skip this part.. (probably the only time you will install a bullet guide is when you decide to go with a different trunion (that is stripped/New/Virgin) or go with a new milled receiver that does not have one installed - like in this case below..)
If your kit came with a TRUNION (sheet metal receiver kit/ Flat receiver kit), it came with a bullet button installed. So skip over to post # 8

There are different bullet guides for 7.62, 5.56 and the 5.45. You can reuse one from your de-milled kit


http://i280.photobucket.com/albums/k...100_0300AA.jpg

http://i280.photobucket.com/albums/k...100_0204-1.jpg

Now pressing in this rivit is a cake..
http://i280.photobucket.com/albums/k.../100_0300A.jpg


This is how it looks turned upside down. With the round rod at the bullet button face supported.
http://i280.photobucket.com/albums/k.../100_0300c.jpg


Now simply crush the rivit like this ..
http://i280.photobucket.com/albums/k.../100_0300b.jpg http://i280.photobucket.com/albums/k.../100_0300d.jpg

fredieusa 06-13-2009 1:26 PM

This is how it looks crushed. in the photo below I meant to write diameter and not circumference. IOW twice as wide.
http://i280.photobucket.com/albums/k.../100_0300e.jpg

http://i280.photobucket.com/albums/k.../100_0300f.jpg

Finally the bullet guide is done!
http://i280.photobucket.com/albums/k...2/100_0301.jpg

fredieusa 06-14-2009 2:10 PM

Issue discussed in this post is very uncommon. i have encountered this only once before. Both times it has occurred on domestic MILLED receivers. If it helps you to know, they were on different makes, this pretty much covers the domestic milled market (other than Arsenal)

Incorporating this to "fix" your company made name brand is also not advisable as it will most likely throw off your head-spacing. These details are only noted by careful and detail oriented builders, others simply overlook.


As shown in the picture, the bolt does not contact/meet the receiver at the charging handle side. Shown with a blue arrow.
The point of contact is on the point shown by the red arrow.
The area taken up on the point of contact (red Arrow) is very small. Usually it is on the other side (opposite).

It is common to see bolt making contact with the receiver/trunion on the charging handle side. This gives a wider area for the continuous impact over long time.


IDEALLY, we should have the bolt touching at BOTH locations, but that is RARE.
http://i280.photobucket.com/albums/k...l/100_0972.jpg
http://i280.photobucket.com/albums/k...l/100_0975.jpg

The gap is about 1.25mm ( .0495" roughly) wide. I have decided to decrease this gap by shaving off both, the receiver/trunion and the bolt carrier. Here the receiver/trunion has some material filed off (about 0.6mm) Circled on RED

http://i280.photobucket.com/albums/k...l/100_0983.jpg


Here I noticed that the bolt carrier is slightly convexed out, so I make that area smooth (circled in RED). This gave me the other .6mm or so needed.

As I tried the bolt carrier, it still did not want to make contact at the desired location. The carrier was making contact with the receiver at an undesired location and that too was smoothed out - Circled in BLUE.

http://i280.photobucket.com/albums/k...l/100_0985.jpg


With a little more nip tuck (filing and polishing) I have even contact on BOTH points on the receiver/trunion!
This will help dissipate the pressure created by the constant pounding of the bolt during cycling.

I use a marker to confirm even contact.

http://i280.photobucket.com/albums/k...l/100_0986.jpg

fredieusa 06-15-2009 5:41 AM

These steps are imperative if you want a smooth action AK.
You can get yours as smooth as one that has been through 1000's of rounds
without wearing out the barrel, ejector, extractor or the firing pin.


Run the bolt head on the rails, there is a good change it will be stuck at the ejector. Use a file to get the area of the ejector down so the bolt head may pass freely. Be be careful not to over do it.
The whole point is to have the largest ejector possible while attaining a smooth clearance.

http://i280.photobucket.com/albums/k...l/100_0938.jpghttp://i280.photobucket.com/albums/k...l/100_0942.jpg

Now although it does pass very smoothly, it is slightly canted/pushed towards the selector side..
That means it may still snag if run complete with a bolt carrier.

http://i280.photobucket.com/albums/k...l/100_0944.jpg

So to make certain we have a smooth/snag free sliding of the complete bolt assembly, (past the ejector) we try it out.
Needed a little more tweaking.. but i got it just right.

http://i280.photobucket.com/albums/k...l/100_0968.jpg

fredieusa 06-15-2009 6:07 AM

Having installed the bullet guide we will check to see how it operates. It also assists in the turning (and locking) of the bolt head!
As the barrel is not yet installed, we have plenty room to get in and smooth things out with a file or dremel - if need be.


Again, we start with the bolt head alone and see now it rides into the locking lugs AND turn. The objective here is to achieve the smoothest ride possible while the bolt head rides (as far as it will go) up and locks into the lugs

All new bolt heads have sharp edges and corners. I used a new marker to lay a thick black coat on it so I will know the snagging points.


Note only the locking arms/lugs and their edges is where I am interested in ...

http://i280.photobucket.com/albums/k...l/100_0951.jpg

Here it rides in decent, (can easily get smoother)
http://i280.photobucket.com/albums/k...l/100_0952.jpg

And now it locks (turns about 20 degrees towards selector side).It took a lot of time and wiggling for it to lock and about just as much getting it loose. I repeated this step a few times to understand the relationship and snag points (each rifle is unique when you reach this step). I also have the black marker on the bolt head to aid me.
http://i280.photobucket.com/albums/k...l/100_0954.jpg

And here we get to see the highlights.
http://i280.photobucket.com/albums/k...l/100_0959.jpg

fredieusa 06-15-2009 6:26 AM

Never touch the bolt head face. Just the edges that need a little POLISHING..
I used my file very gently and here it is.

After repeating this process {of using a marker and filing the resistance points} about two times, this bolt head is rather smooth


http://i280.photobucket.com/albums/k...l/100_0962.jpg

I also had to fix/smooth out the receiver/Trunion
http://i280.photobucket.com/albums/k...l/100_0303.jpg

http://i280.photobucket.com/albums/k...l/100_0304.jpg

Here is the starboard side.
Note - I have smooth out the surfaces leading into the bolt head locking area but NOT decreased the locking lug face area

http://i280.photobucket.com/albums/k...l/100_0305.jpg

fredieusa 06-15-2009 7:31 AM

Now that its running smooth by itself, I will try it out with the carrier (just as we did for the ejector).
This is important as without the carrier, my fingers may adjust to tension and give the illusion of a smooth action. The bolt carrier will keep the bolt head in line.

http://i280.photobucket.com/albums/k...l/100_0966.jpg

Now trying with the carrier...
http://i280.photobucket.com/albums/k...l/100_0968.jpg

Not as smooth as i would like.. and so I take note of marks yet again.
http://i280.photobucket.com/albums/k...l/100_0965.jpg

But this time I don't use the file. I simply use a buffing wheel..

http://i280.photobucket.com/albums/k...l/100_0960.jpg

Now I will try it out again WITH the bolt carrier..AND the recoil spring..
http://i280.photobucket.com/albums/k...l/100_0969.jpg

You should not use the charging lever to check action smoothness as it cants the carrier and it WILL jam. as shown here..
http://i280.photobucket.com/albums/k...l/100_0971.jpg

fredieusa 06-15-2009 7:08 PM

The way I do it.. I place the piston against a solid surface and push the receiver body. This gets the piston moving straight, back and forth. You may also simply push down on the piston with one hand while holding the receiver body in the other.

Make note to observe the bolt head riding and locking smoothly...

http://i280.photobucket.com/albums/k...l/100_0970.jpg

And we have a smooth action ! Really!
To have a finished rifle that is really smooth, you will have to tweek the FCG (fire control group) also.

fredieusa 06-15-2009 9:35 PM

Barrel Instillation - Our barrel is white with no holes. Its a virgin too..

This section may also be referred to when changing out a barrel or installing a new one in any kit.
i.e. AMD kits come without original barrel.

Barrel Address / Markings. This is a matter of preference, I like all (or as many as possible) my barrel marks, proofs, bore info to be facing up. They should be visible as soon as the upper hand-guard is taken off. So I make that determination now as to which side is up.

http://i280.photobucket.com/albums/k...l/100_0306.jpg

Now for the extractor cut out.
The depth of this cut into the barrel is about .050" That is roughly the average I have taken.

http://i280.photobucket.com/albums/k...l/100_0311.jpg

BTW there are NO hard and fast rules on this cut. Use a grinder or a dremel. The smoothness comes with experience. You may want to practice on a metal chunk before destroying a good barrel. Here is a late model Bulgarian factory cut. This is what "the factory" is doing now.
http://i280.photobucket.com/albums/k...l/100_0935.jpg

The cut out should be wide enough to accommodate the area marked below on the bolt face. And yes, the bolt head does turn/swing to lock.
http://i280.photobucket.com/albums/k...l/100_0309.jpg

Another illustration

http://i280.photobucket.com/albums/k...l/100_0308.jpg

fredieusa 06-16-2009 9:56 PM

Now we move right along and take barrel - trunion measurements.

NOTE 01 - factory kit Yugo barrel and trunions are just right and do not need to be fitted. Fact is the M70AB2 virgin kits have all parts - RSB, Lower Hand Guard retainer, Gas block and FSB matched up and they dont need to be trimmed / turned down. Using another trunion (milled receiver in this case) may need fitting.

NOTE 02 - You will often see numbers stamped on your parts (FSB, BG, RSB, Trunion) ranging from 1 to 4. These are production limit control numbers and have nothing to do with quality or accuracy as some believe. This method of grading production is very common in any mechanical production shops. It tells the operators when to change out old tooling so the product remain within tolerance.

1 is for under-size, 2 for standard, 3 for over size and 4 for way over size. Parts were grouped accordingly and assembled.
The factory/Arsenal also mixes and matches parts so you may end up with a 1 and 2, its no big deal. This does not take away from your value or originality.


Here my measurements from the trunion come in at .8985"

http://i280.photobucket.com/albums/k...l/100_0312.jpg

And the Barrel at .9075. The difference is just too great.
http://i280.photobucket.com/albums/k...l/100_0313.jpg

Ideally the barrel should be turned in a lathe between the centers (using live center) so you may also check that the outside diameter is concentric. BUT we have to do this without a lathe.. so here goes..

We need to bring the difference between the barrel and the trunion/receiver down to .003 from .009. (The barrel stays slightly over sized). We do this by enlarging the trunion hole! Here are our $6 fixings that will replace a lathe.

Glue
Double sided tape
Drill bit anywhere between 1/4" - 1/2"
assorted Sandpaper

http://i280.photobucket.com/albums/k...l/100_0314.jpg

Using the material above, fashion yourself a drum sanding device that will barely fit into the trunnion. And sand away for 10-15 seconds at low speeds periodically checking the diameter... till you are done.

The sanding will self center as it moves as you are using free hand. It is important you do this with a hand held drill to make certain the material taken off is uniform!


http://i280.photobucket.com/albums/k...l/100_0315.jpg


Now that the trunnion and the barrel are within limits, we lube them up
http://i280.photobucket.com/albums/k...l/100_0300.jpg

Now you may start to press the barrel in - Have your extractor cut positioned right, eye blinking later will not help. You will have to press out and start over..

The smoothness of the barrel pressing will depend upon the tonnage of your press and how tight the fit between the barrel and the trunion/receiver is.

If you are using a 12T press and the barrel "bounces" forward instead of creeping (despite the use of lube), the fit is a little too tight. Or you may just use a heavier press. If your barrel-trunion fit is too tight (should you decide to use a heavier press say a 40T), you risk cracking your your trunion.

Cryogenic cooling and then pressing does not help. Also it may cause rust over time, as the moisture in the atmosphere freezes on the cold surface right away.

Headspacing is adjusted in fractions of a MM. If, with each bounce you move .5mm or more, it is no good.


http://i280.photobucket.com/albums/k...l/100_0316.jpg

fredieusa 06-16-2009 9:59 PM

This little step in the bullet guide (marked with red arrows) is where you need to push your barrel to. Keep it slightly shy if you can ~ .5mm
http://i280.photobucket.com/albums/k...00_0300f-1.jpg

Here is a barrel pressed in roughly to that point
http://i280.photobucket.com/albums/k...l/100_0349.jpg

fredieusa 06-17-2009 11:16 AM

incorrect headspace gun going boom in at the wrong end ..
http://www.youtube.com/watch?v=rQep2nWGfBw



Now I correct and adjust the head-spacing. I have to determine whether the current head-space is small, large or correct. There is no such thing as almost correct. I use an assortment of devices to accomplish this.

Assorted make (DUMMY) cartridges with no powder or primer
Scotch Tape
Head-spacing gauges (not a must if you have the above - That's right)

The variation between a Go Gauge( in specification) and No Go gauge ( out of specification - larger) is only .0045" to .005"

http://i280.photobucket.com/albums/k...l/100_0350.jpg

Assuming we don't have go - no go gauges, we can create out own.
Three layers of the scotch tape adds roughtly .005", to a regular cartridge making/representing a NOGo gauge.
The regular cartridges, without any tape on them will suffice for Go gauge.


So here is our NO GO gauge..
http://i280.photobucket.com/albums/k...l/100_1002.jpg


Inspect your chamber first to be certain it is clean. With all the metal shavings and chips around, you can not be sure.

1 - Using No go gauge - Action does NOT lock, bolt head does not seat and lock - This is normal, move on.

2 - Using No go gauge - Action DOES lock - Head Space is too great. Barrel needs to be pressed IN a little more, you are doing fine.

3 - Using GO gauge - Action does NOT lock, bolt head does not seat and lock - Head Space is TOO tight OOps. Reverse the press jig and press the barrel OUT some. You over pressed it.

4 - Using GO gauge - Action does lock - Beautiful. we have correct head space. Repeat steps 1 and 4 with recoil spring several times.


http://i280.photobucket.com/albums/k...l/100_0317.jpg

http://i280.photobucket.com/albums/k...l/100_0318.jpg


It is tight headspacing that is more dangerous. It results in the cartridge making a tight contact with the bolt head without the bolt head being locked in place. Pulling the trigger does set off the round, causing an explosion 8" from your eyes, having enough energy to shatter receiver, strip the magazine or rounds by blowing out the mag floor plate. And all sorts of stuff that make good stories and conversation pieces.
Here is great video checking/fixing headspace.

http://www.youtube.com/watch?v=8HR3RnBNVTA
http://www.youtube.com/watch?v=KICBv-0U87Y
http://www.youtube.com/watch?v=3HfJFg81BuM&feature=fvsr

fredieusa 06-17-2009 1:29 PM

Pressing in the Rear Site Base (RSB)..

This RSB self centers on front trunion, as tolerances are tight. The receiver/trunion is 24mm even and the RSB width is 23.90mm

The barrel at the point (where RSB is going to slide over) is 18.6mm and the RSB hole is almost 18.55mm. Lube it up.

http://i280.photobucket.com/albums/k...e/100_0351.jpg

Push on the barrel and no where else. Remember, we don't have a BARREL RETAINING PIN YET. If you apply pressure anywhere else other than the barrel, you will be affecting/disturbing the HEADSPACE. I keep it this way so I can adjust for "cant" - Avoiding canted Gas block, canted Front Site Base FSB.

http://i280.photobucket.com/albums/k...e/100_0352.jpg

The RSB will stop once against the trunion/receiver, as shown with RED arrow. Again dont keep this tight. It may push on the trunion. Let go as soon as the RSB reaches there. Dont push on it.
http://i280.photobucket.com/albums/k...e/100_0371.jpg

Clean out the extra grease. It keeps the project neat and tidy, plus it helps with refinishing later. Check the RSB so it is square and not canted. If it is canted, get that 3 Lb. mallet out! You can also get creative and use a vice to correct the cant. Be careful not to ding up and marr the project.
http://i280.photobucket.com/albums/k...e/100_0353.jpg

fredieusa 06-18-2009 8:26 AM

Fitting the lower handguard

Its a Virgin kit, things just don't add up themselves...


http://i280.photobucket.com/albums/k...d/100_0940.jpg

Little at a time and check for fit often. If you take off more than you should, it will rattle and have a loose fit! Then you will have to rebuild that surface with sawdust mixed with epoxy.. Maybe i'll include this in my refinishing thread
http://i280.photobucket.com/albums/k...d/100_0941.jpg

Now the front, same thing..Little at a time and check for fit often. If you take off more than you should, it will rattle and have a loose fit! Then you will have to rebuild that surface with sawdust mixed with epoxy..

http://i280.photobucket.com/albums/k...d/100_0942.jpg

How is the fit? Something to be proud off ?? Oh yea!
The sharp edges on the wood are natural, will get a slight smooting once you put on lacquer or your Poly-Urethane.
If you dont like them this way, you can always smooth them out on an abrasive wheel or just 2 minutes of hand sanding by cupping the abrasive sheet in the palm of your hand - Topic for refinishing..


http://i280.photobucket.com/albums/k...100_0945-1.jpg

fredieusa 06-18-2009 9:28 AM

Now while you have the lower hand guard snugly seated in your Rear site base with the lower hand guard retainer as pictured in the photo above MARK the front end of lower hand guard retainer on the barrel.

Use a sharp scriber. You dont want the scribed mark to be 1mm away from the true edge on the barrel.

http://i280.photobucket.com/albums/k...d/100_0511.jpg

In THIS case, distance between the edge of the HG retainer and locking lever (axis center) is 5.93 mm

http://i280.photobucket.com/albums/k...d/100_0512.jpg

I used different files and carved it out. Its better to stay towards the receiver than the muzzle.
If the locking pin does not want to close/lock/swing you will have to go deeper and/or towards the muzzle.
If it turns out loose, well.. you went a bit too far towards the muzzle, now you will have to tac weld the divit toward the muzzle and start with a file again. Bear in mind we are talking in fractions of 1mm here..

Now if we had a mill, we will be using a 15/64 ~.22" end mill and go about .11" into the barrel..

Here I have managed to achieve a very tight and snug fit. A good fit means that the locking lever will freely swing while making a constant contact. The retainer itself (when locked in place) will have minimum PLAY, specifically to the left or right!


http://i280.photobucket.com/albums/k...d/100_0946.jpg

fredieusa 06-18-2009 11:27 PM

Upper Handguard

To install the upper handguard, you may need to only file down the surface indicated with the RED arrow.

As with all other things, take your time doing this. Over filing will result in a wobble and clatter...
To correct a wobble/loose fit, you will be back at the welder and then filing..


http://i280.photobucket.com/albums/k...d/100_0997.jpg

here i get a very tight and snug fit. So snug, that the upper hand guard/piston tube has no wobble!

http://i280.photobucket.com/albums/k...d/100_0385.jpg

fredieusa 06-19-2009 1:12 AM

Installing the Gas Block(GB) and Front Sight Base (FSB)

Measurements - The barrel comes in at 16.065mm and the GB is at 16.02. This is borderline, so I go ahead and start to press. I have found the yugo M70's kits to be very good when it comes to fit. Should your difference be over .04mm - .05mm, sand down the GB hole as we did for the trunion..

You can go about this in a few ways. Suite yourself.

I do not press in 100% the GB and the FSB, because I suffer from a compulsive disorder involving matters such as proper line-ment.
Just cannot stand the "cant" - A term used to describe the GB or the FSB leaning to one side, not in a perfect line.

After you lube it up and place the FORWARD SLING MOUNT LOOP, line up the GB as best and centered as you can.. Observing the GB from the rear sight as if you were aiming, will give you a good idea.


http://i280.photobucket.com/albums/k...e/100_0386.jpg

Then I go ahead and press in about 1/4" ONLY.

Be CERTAIN that you (the ram is) are pressing on the barrel

we have not pinned the barrel or the RSB yet !!

This allows me to correct the cant later, using a mallet.


http://i280.photobucket.com/albums/k...e/100_1036.jpg

Now that the GB it abot 1/4" on and will not simply fall off, I take linement again.
here I use a common sewing thread to line up my GB.
I hold in place the thread from t he very end of the receiver (through the RSB) to the muzzle.


http://i280.photobucket.com/albums/k...e/100_0908.jpg

Use a mallet to line the GB up, if needed.

http://i280.photobucket.com/albums/k...e/100_0909.jpg

I used a laser here. Kinda helps. You will have to get the laser projection just right and then check for linement.
Line up the muzzle and the rear trunion. Set it in place and then look for variations on the Rear Site and the Gas Block


http://i280.photobucket.com/albums/k...e/100_0911.jpg

Now put together your Front Site..

http://i280.photobucket.com/albums/k.../100_05611.jpg

fredieusa 06-19-2009 1:12 AM

Lube up and set the Front Site Base.. (FSB)
Measurements - the barrel come in at 15.05mm, the FSB at 15.03.
I would rather have a tighter fit... if only the FSB was 15.01 - 15.02mm
But this is not a big deal.

Set it in with a mallet


http://i280.photobucket.com/albums/k...e/100_0913.jpg

Check for linement again. I am really getting to like this laser checking. Its one of the cheap ones but projects a horizontal, vertical and a 90/180/360 degree self leveling projection!!

http://i280.photobucket.com/albums/k...e/100_0917.jpg

Remember to place the hydraulic ram on the barrel. We have NOT yet pinned the barrel and the RSB yet!

Now press in the FSB all the way. Check for Cant AGAIN.
Then press in the Gas Block to its final position.


http://i280.photobucket.com/albums/k...e/100_0919.jpg

fredieusa 06-19-2009 1:14 AM

Here is what the muzzle looks like. Pushed too far ? NO
But do not push any further than this..
Pushing further will create a gap between some of your muzzle attachments and the FSB


http://i280.photobucket.com/albums/k...e/100_1039.jpg

Here is a better look at the barrel threads. Also the fit between the Gas Block and the upper hand guard is visible.

http://i280.photobucket.com/albums/k...e/100_1040.jpg

Time to try on the bayonet. It should fit nice and square. Resting on all places it should.

http://i280.photobucket.com/albums/k...l/100_1044.jpg

Almost getting some form here..

http://i280.photobucket.com/albums/k.../100_10411.jpg

fredieusa 06-19-2009 1:14 AM

We will now drill for the Following (in the order stated).. Barrel retaining pin (1), RSB retaining pin (1),
GB retaining pins (2) and FS retaining pins (2).

Here are some measurements for the M70AB2.

Barrel Pin (1) - Pin Diameter is 7mm/0.2755"
RSB Pin (1) - Pin Diameter is 4mm/0.1575"
GasBlock Pin (2) - Pin Diameter is 2.5mm/0.0985"
FSB Pin (2) - Pin Diameter is 2.5mm/0.0985"

I highly recommend measuring your drills. Just because it says it is 5MM, does not mean it is.


Drilling takes skill - Know your cutting angle, speed and feed rate. These perimeters (will change) depend upon the work material, while using the same drill bit. Check out mmsonline.com/article.aspx?id=14722

i.e. While drilling the barrel retaining hole (7mm), my drill speed was 650 RPM and feed rate was .0015"-.003" per second (roughly as I am doing this on a drill press by hand) with a point angle of 140 degrees..


Here we start on the barrel retaining pin. Some measurements for your pleasure.

http://i280.photobucket.com/albums/k...s/100_1055.jpg

Scribe a line 5.5MM from the top of the receiver and about the center of the trunion tab. Drilling at this point at 7MM will give you a clearance of about 3mm+ at your chamber bore.

http://i280.photobucket.com/albums/k...s/100_1056.jpg

We don't want our drill hole to be uneven as it will lead to potential issues apart from aesthetics.

http://i280.photobucket.com/albums/k...s/100_1057.jpg

I position the drill off the drill point so i can eye-ball it. I adjust the barrel so the drill is equidistant from my designated reference points. Once this is done I am certain barrel retaining hole will be all square and not canted. On a lathe it would have not been an issue.

http://i280.photobucket.com/albums/k...s/100_1059.jpg

Use cutting oil liberally. I give a squirt every 15-20 seconds. After you are through drilling, use a reamer if you have one.

http://i280.photobucket.com/albums/k...s/100_1060.jpg

Measure 20 times, drill once!

http://i280.photobucket.com/albums/k...s/100_1061.jpg

fredieusa 06-19-2009 1:15 AM



Rear Site Base / RSB

Square it up, just as we did the trunion for the barrel retaining pin.
Use cutting oil liberally. Drill.

http://i280.photobucket.com/albums/k...s/100_1062.jpg

http://i280.photobucket.com/albums/k...s/100_1063.jpg

Take a moment and check AGAIN for cant (Gas Block and Front Site base). You want to be certain this time around for obvious reasons..

http://i280.photobucket.com/albums/k...s/100_1064.jpg

Note reference points for the Gas Block and adjust so the drill is equidistant from the drill when held vertical and parallel.

http://i280.photobucket.com/albums/k...s/100_1067.jpg

Drill both holes. Use cutting oil liberally. Insert the pins as we go along.

http://i280.photobucket.com/albums/k...s/100_1068.jpg

For the Front Site Base - Take reference points and adjust. Drill and pin.

http://i280.photobucket.com/albums/k...s/100_1073.jpg

fredieusa 07-04-2009 7:15 PM

You may want to install the detent pin AFTER you have completed applying a finish to the rifle i.e. Bluing or Parkerizing.
Springs must be spared from process such as Oxidization/ Rust / Bluing / Park'ing.


After cleaning all the shavings from the detent pin hole, insert detent spring and detent.

The detent has to be lined up just right that will allow the retaining pin to be installed.
I hold the detent pin in position by screwing a muzzle device to a desired location.


http://i280.photobucket.com/albums/k...s/100_1104.jpg

The retaining pins may be simply hammered in. If the fit is tight enough and hammering results in mushrooming of the pin, you may use a press. This concludes the detent pin instillation.

http://i280.photobucket.com/albums/k...s/100_1105.jpg

fredieusa 07-05-2009 11:26 AM

Virgin trunion does not have the stock holes milled out. Yes it is considerably thick, hence the use of the word milled.
This can be accomplished by drilling on a drill press. It may also be accomplished by a hand drill.

Advice here is to NOT go by the receiver, instead get your measurements by the stock and its components to get a sold wobble free fit. This may mean egging out receiver holes and fixing them later.


http://i280.photobucket.com/albums/k...k/100_1045.jpg

Below, I assigned alphabets to decrease confusion and typing.
Item #E has six holes. They are not all same. Three are larger than the others.
Large one is where you insert the pin #H from.
Item #C had two axis pin holes and they both are also NOT same!
Large one is where you insert the pin #H from.
Item #H All three are the SAME.


http://i280.photobucket.com/albums/k...k/100_1106.gif

Insert item #C as shown and the stock. line up the holes.
Insert #A inside #B and install (from the left side) in the receiver through the stock


http://i280.photobucket.com/albums/k...k/100_1107.jpg

Insert #D inside #E.
Insert into receiver through #A
Line up Hole in #A and the long slot on #D
Insert #H (pin) through the holes. This pin will protrude out from both sides on #A
Insert this pin #H into the slot milled on the right side of the trunion/receiver (shown in the picture below - bottom-right, red arrow)


http://i280.photobucket.com/albums/k...k/100_1108.jpg

Hand tighten #E onto the threads of #A. Line up the hole with slot on #A.
Install pin #H. Use a punch or a mallet to get it flush down with #E

Insert #G followed by #F, keeping the pin hole in #F vertical


http://i280.photobucket.com/albums/k...k/100_1109.jpg

While holding in the push button #F, line up the holes on #C, #A, #F and #D and insert the last #H through them(as shown below-left) Tap the pin #H down and it will hold tight

http://i280.photobucket.com/albums/k...k/100_1110.jpg

You are Done installing an under-folding stock!
CA residents continue below...

fredieusa 07-05-2009 1:10 PM



Fixing an underfolding Stock!

For California residents only. CA residents have to deal with issues pertaining to Folding/Collapsible Stock and Over All Length.

Below method is simple.. (I find it the simplest) No additional hardware, no removal of hardware and best of all, no mods.
Just incomplete instillation and we get our fixed stock.

This situation cannot be corrected without taking off the grip.
So one will need a screwdriver and a punch to get it working again.

------------------------------------------------------------------

All Under Folders should (as in the pic below) have pin access holes at the bottom shelf of the receiver.
If you do not, drill some! to get it to be correct anyway..

Insert the last pin #H (in the LAST step as stated in the post above) from the bottom and let the very end be flush with the receiver.
This WILL NOT ALLOW the push button #F to be depressed.

If you installed the pin from above, use a punch to push it INTO the access hole in the receiver


http://i280.photobucket.com/albums/k...k/100_1111.jpg

fredieusa 07-07-2009 4:38 PM



Gas Port Hole Drilling

The gas Port is pinned and is set in place. Drilling the gas port hole will complete your rifle's transformation to a semi-automatic.
Given this fact, you may want to leave this step to the very end given your legal circumstance.


Your Gas Block already has a hole drilled though it. You can gauge the hole size by inserting different drills in.
I use drill size # 27 (~3.61mm). I guess you can also get-by using a #28 (~3.53mm)

Simply use a hand-held drill and drill away. Use lube/cutting oil. Be careful not to over drill as you don't want to disturb the rifling on the "other/opposite" side.

Once you are through drilling, clean thoroughly using a brass bristle brush. Check for obstructions.
Use a reamer if you have one, I always do.



http://i280.photobucket.com/albums/k.../100_05612.jpg

fredieusa 07-07-2009 4:38 PM

Test Fire

For all intents and purposes you have a semi-auto rifle.

Other than the test rifle, I usually take 30 to 50 rounds of assorted ammo. All different makes of mags I can lay my hands on, and Basic tools.

Visually check for any barrel obstructions and check head spacing once again. I usually fire assorted ammo from assorted mags. A file can fix almost all issues permanently on the spot.

You may also perform an informal sight-in. No point taking a rifle for finishing with canted GB or FSB !:eek::o:(:mad:

Refinishing the Rifle

Now that the rifle passed the range trip, it is time for TAKING IT ALL APART FOR REFINISHING.

Remove the stock
Muzzle device (and detent pin)
Front site post/blade (also night site in this case)
Rear site (including leaf spring)
Upper Handguard
Lower HandGuard
All BCG and FCG parts
Possibly press out the barrel also (for varying reasons)

Final Assembly

Put it all back together. Look out for scratches, dings and scrapes.

Final Range Test and Sighting-in

10 Rounds will do it.

Knowing you have saved yourself anywhere from $500~$700.00
calls for a special toast!

Cheers.


http://i280.photobucket.com/albums/k...2/100_1152.jpg

skanless 05-14-2010 8:23 PM

Nice work. :thumbsup:

strangerdude 05-18-2010 10:22 PM

Wow, how does one learn these skills? Is there a good book on AK building?

Ryan in SD 07-20-2010 4:10 AM

amazing posts, that is sooo much work, hopefully someday I can do that too.

straykiller 08-05-2010 11:00 PM

great post thank you, I've built a 1919a4, and a sten mk3 and have been looking for something a little more complicated, i think you just decided it for me, ill have to lurk around for awhile soaking up all the info i can, thanks again and great job.

btw your sigs fu*kn hilarious, gotta watch out for those shrouds that go on you shoulder and go up.

WTSGDYBBR 12-26-2010 2:34 AM

A+ Thread love how you had a stamped and converted it into a milled receiver

bravosd6 07-08-2011 2:19 PM

Jesus. This looks like a lot of work.:(

Looks nice though. Super Clean!! Probably Shoots like dream!

nicitaja 07-15-2011 9:46 AM

I used to have a sticky to the build that originally had the milled build documented, (at least I thought I did). In the illustration on the barrel face cuts, it even says (shown in the next pic) but that pic is not there.

Can you redirect me to it, I swore I've seen all those pics but when assembling the whole thing on that milled receiver.

Thanks in advance.

outlawdaveyjones 09-28-2012 1:27 PM

Fricking nice dude!!! You have some real talent and patience to build a gun from scratch! Everything is on point as I know once holes are drilled, they cant be undrilled. I've built 4 AR platform rifles from stripped receivers and converted 2 Saiga's (12 Gauge & .308) just by watching videos and first hand experience, but I'm very blown away at all these pictures of your build. I'm assuming you went to Gunsmithing school to perform these intricate processes or just trial and error after all these years? I could spend hours and days building and converting rifles. I think I need to make this into a career!

hellayella 10-20-2012 2:24 AM

u got some mad skills!

wpage 01-08-2013 1:48 PM

Amazing... How much different is the Russian model?

hotelsunseo 01-21-2013 8:38 AM

Awesome!

4thSBCT 02-01-2013 12:16 PM

Quote:

Originally Posted by hotelsunseo (Post 10272345)
Awesome!

No Doubt!

This thread is all I needed to learn how to populate a virgin barrel. Freddie shows everything but the sink.


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