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VZ58 Build

Tracking my progress.  I know this isn't "technically" an AK but since it is based on the design I'll place it here.

The VZ58 is a challenging build because of the extra steps involved in comparison to a normal AK.  That, and the fact that US-built parts are either cost-prohibitive or simply doesn't exist, and you've got yourself a challenge! 

  • Compliance Parts
  • Barrel Removal
  • Rear Sight Removal
  • Barrel Extension
    • Building the Extension
    • Attachment
  • Scratch-Built Receiver
  • Piston
  • Fire Control Parts
  • Headspace
  • Finish

 

COMPLETE -

       

Here you can see where I welded an extension onto the magazine release lever.  Saved $25 on the commercial one.  It makes for VERY FAST magazine changes.

Vids of test firing - she works!  :) 

http://cid-5b54fc51a7917265.skydrive.live.com/browse.aspx/Videos

   

Compliance Parts

The complete parts list found on a VZ-58 that is ATF-legal (aka with permanent muzzle attachment):

(01) Receiver
(02) Barrel
(03) Muzzle Attachment
(04) Gas piston
(05) Buttstock
(06) Pistol grip
(07) Handguard
(08) Disconnector
(09) Trigger
(10) Hammer - I'm counting the striker as a hammer for the purposes of compliance...
(11) Sear
(12) Bolt carrier
(13) Bolt
(14) Floorplate
(15) Magazine body
(16) Follower

Unlike an AK, the VZ has a separate sear.  Thus the parts count is 16, so for the "10 or less" quota, I need 6 parts.  This is how I've worked them out so that I can keep the original Czech furniture:

  1. receiver
  2. muzzle extension
  3. piston
  4. trigger
  5. sear
  6. disconnector

Rumor has it the ATF intends to classify the receiver stub, when used with a "repair channel" build, as a trunion.  That would put the parts count with a "repair channel" build at 17 parts for compliance parts count purposes.  An obvious choice for that part would be to construct new floorplates since they are sheet metal and fairly easy to construct.

 


Barrel Removal

I had originally removed the barrel to assist with handling of the receiver parts and the barrel extension.  I have determined an easier way to both tasks and keep the barrel in place, so I will not recommend removing the barrel unless it is ABSOLUTELY necessary!  The barrel removal is simply not needed unless the rifle needs a headspace adjustment.  If you are using one of the 80% "repair" sections, I recommend just leaving the barrel in place.

Removal of the barrel pin is the hardest part, since the barrel pin has a considerably smaller diameter than a standard AK barrel pin.  I was able to finally press mine out by careful placement of shims underneath the receiver section and a cut-off (actually broken-off) punch that was the correct diameter. 

           

Once it started going, I switched to a section of an Allen Wrench that I sacrificed for the job.

   

Note how long the journal is in comparison to an AK journal - it starts hard but does get easier. 

   

Bottom line, don't remove the barrel unless you must!

 

 


Rear Sight Removal

The rear sight leaf is similar to an AK, but it has a notch to keep it from flipping up.  It took me a while to figure this one... a good, CAREFUL push with a punch can get the spring down enough to make it start moving.  Just wear gloves in case you slip and smack your hand!

   

 

 


Barrel Extension

The factory barrels are 15.5", so you need a barrel extension.  The "factory-styled" muzzle brake is perfectly suited to this, since like an extended AMD-65 brake, it can be permanently attached to extend the barrel to the legal 16" requirement.

I fabricated and attached the extension before I attached to the receiver to avoid any interpretation that I had manufactured an SBR.  It is difficult to determine "when" in the build process the pile of parts actually 'becomes" a rifle, but I intended to err on the side of legal caution, so the extension came first...

Building the Extension

I experimented with one of those old $1.00 FAL G1 grenade launchers as a donor.  It did work, but it wasn't as nice as I'd like it.  SO...

Hotbarrel to the rescue!  I worked with him to create as close a copy to the original as possible, using the pics floating around out there.  IT ROCKS!  I definitely recommend Hotbarrel's work to anyone.   

 

Blind Pin Attachment

To make it permanently attached (a legal requirement), I have elected to blind pin this one.  Per the ATF blind pin documentation (check my Resources page), the pin must be at least 3/32" diameter and .03 - .05" deep.  I threaded the hole for 6/32 which is larger than 3/32".  3/32 = 2.5mm approximately.  I drilled this to just at .046" depth and welded over.  It is SOLID!  I don't think it will budge even if I dropped it on the muzzle.   

The end result: 17.25" barrel length as measured from the closed bolt.  That's 1.25" over the minimum 16" requirement.  :)

Hotbarrel's extension has a recess for the original retainer pin.  This gives it the original look.

 

 


Scratch-Built Receiver

Note the location of the auto sear.  The approved-and-legal semi design puts a metal shim in the way of that arm so it cannot be installed.  Therefore, I intend to follow suit and weld a metal block to eliminate any chance of the auto sear from being installed.

I started out with the metal scraps from a de-milled kit... just like with the semi-only MG42 build.  I think these metal scraps are all from the same rifle but I am not certain.

Here's the scrap section that has the machined sear notch.  This is the section where I must install the block:

Cleaning up the chunks - note the wide gaps.  This will require more welding than my MG42 builds!

           

I used many more dremel cut-off and polishing wheels than I expected.  I used the thin wheels to better get into the small areas around the rails.

The scraps were all bent out of alignment.  I had to do a considerable amount of bending and fitting to get them to line up properly.  I'm don't think that I got it 100% flat on the sides, but it doesn't seem to matter so much.  The important part is the alignment for the bolt carrier, fire control parts, and magazine locking tab.  So long as these three items function, the rest seems to be OK.

   

The fit for the first part of the full-auto sear block.  That is a 3/8" square bar that I'm fitting into place.  That was the "base" for the receiver "legal compliance block" and was the first thing I welded before I did any other work to the scrap parts:

       

Once the full-auto sear block was welded into place, I tack welded the remaining blocking material to fill in the entire area in front of the trigger.  Then I tack welded the receiver pieces for an initial fit.  You can see how I used some metal bars and C-Clamps to align the parts:

       

That shim is a copper plumbing tube (1/2" tube I think) that I flattened out and bent over onto itself for more mass to absorb the heat.  I didn't want to over-heat the pieces since they would move when cooling.

   

I had to redo the sections several times because of the movement the contracting action of the cooling metal had.  I could watch the receiver pieces move from side to side when they cooled... quite entertaining!  :)  This was a very time-consuming process due to needing to re-weld the same parts if they were mis-aligned after cooling.  I was able to finally get it to align along the vertical and horizontal.  Short cycles with the welder, big heat sinks, long cool-down times in-between welds, and PATIENCE, PATIENCE, PATIENCE allowed me to get the pieces welded up.

 

I donned my respirator and goggles (and ear plugs!) and dremeled the rails to fit the bolt and carrier.  This took some patience and a good eye to ensure the pieces remained aligned.  It is easy to dig too deep with the dremel and make a notch in the rails, so I took my time and continually tested the fit. 

Ideally, I would have obtained cutters for my mill that could cut the notches, but the dremel worked surprisingly well on its own, even though it was an extremely tedious task.

   

The test fit!  At this point, the 17+" barrel (actually just at 17.25") and receiver came together and fit up well! 

           

 


Piston

This was a relatively simple piston to build, since there are no threads to deal with.  I used 1/2" round bar of 316 SS, and made the rings slightly smaller than the original for easy verification:

 


Fire Control Parts

I cut these out of a block of 4340 tool steel.  "Some assembly required" :)

   

The sear retaining pin was easy to get out, once I found a punch small enough!

   

It took quite a bit of dremel sanding, but I wanted to be sure they would function correctly.  They work!  I can dry-fire the rifle and the disconnector works as expected - I have to release the trigger for the rifle to be able to fire again! :)

   

I made the semi-auto sear and the disconnector thicker than the original.  This, IMO, should help with the wear on the parts because there is more surface area to work with.  The disconnector is nearly as wide as the original striker. 

The trigger, not complete in this pic, is thinner than the original, in order to allow this semi-only trigger to work with the sear block modification of the receiver.  In other words, a normal VZ trigger won't even fit!  Again, this is to prevent installation of the full-auto parts.

I have yet to polish and harden the parts in this pic:

   

 

I cut a notch in the safety selector so that, on the "1" or the "30" setting, the semi sear can operate - this lets you swap to either position which is a nice feature that is basically like a semi-only FAL's safety selector lever.  It (obviously) fires only in semi-auto... the full-auto sear notch on the safety is useless.  I may weld it up to give it a cleaner look.

 


Headspace

 

Headspace is set by the length of the locking wedge.  The locking wedge comes in different lengths.  The length is measured along the axial line when the wedge is "in battery".  The initial headspace is set by pressing the barrel in, just as with an AK.  Secondary adjustments to the headspace setting can be made by using different locking wedges which will alter the bolt's physical location in relation to the barrel.

For most home builders, the different locking wedges probably won't help and most people can probably get away with setting headspace like a normal AK - pressing the barrel in/out and re-drilling the barrel pin hole if necessary.

           

The locking wedges up close - that is a "6" and a "4" in the pic.  Note the measurements on my caliper - I have the "6" reading at a few thousandths longer than the "4".  Someone more in the know on these may be able to confirm I measured them correctly.  I am fairly certain that the Armory would swap out locking wedges during maintenance cycles to account for wear and tear in the field.  This is likely not a necessity for the typical home builder that isn't going to excessively use and abuse a rifle.

           

 


Paint Finish

I am doing a paint-over-phosphate like the original.  I intend to paint this with a basic flat black finish. 

The original "battleship grey" paint is acceptable, however the newer images from various sources online suggest the newer rifles were either offered, or refinished, in a black paint.  The newer rifles are usually seen in Czech commando "action shot" pics with the new all-black furniture.  I plan to keep the bakelite composite furniture along with the factory folding stock. 

This is the result of the phosphate finish using concrete cleaner.  I heated it in a stainless steel pot on the BBQ grill. The stripes are the weld beads and are due to the differences of the metal properties from both the receiver and the weld material.  I believe the weld material is common 1018 steel but I am not certain on that.  The original receiver material took the phosphate much more readily, and heat treatment may have contributed.

The inherent heat problems due to welding with a flux-core MIG welder creates "valleys" between the weld bead and source metal.  I finished over the small surface cracks with bondo to provide a clean, smooth surface under the paint, then sanded smooth with 220 grit.

Paint will probably be with duracoat after the range test and degreasing... stay tuned.