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4 Aug 2014 - mkillebrew
VZ-58 parts kit, receiver stub still attached.
Original fire control group, naughty bits included.
Barrel assembly, stripped.
Receiver stub, pin that needs to be pressed out so the stub can be removed.
Square the stub on a drill press, drill the old cross pin out with a #26 bit with some cutting oil.
The new barrel pin will be forward of this one, while cutting into the barrel should be avoided, it will not cause future issues.
Next the barrel is to be pressed out. I used a half inch socket extender on top of a stack of pennies to start it on a 12-ton press
Followed by a slimmer extension to get around the receiver forward of the lug recesses, and again a stack of coins to shim it.
Barrel removed from receiver stub.
Underside of barrel when original barrel pin held it in place.
Barrel stripped of gas block and sight by punching out pins, blasted with 70 grit aluminium oxide.
Removed blocks up close. Note the single pin holding on the gas block, two for the front sight tower. The gas block also retains the handguard cap.
Stock, carrier, cover with springs removed, guard, selector, rear takedown pin, and rear sight are now blasted and ready for cerakote.
The sight needs to be taken off the stub by depressing its spring at the front, then taken down to its three components and blasted individually.
The recoil spring is held on to the cover by the guide wire that snaps into the end cap. release spring tension from the cap and it will disconnect and allow the spring to fly across the room.
D-Technik modified Czech receiver.
Magazine well milled out to accept a double stack magazine
Note drill point under the chamber area where it will be drilled and the barrel pin pressed in.
Unlike the ORF receiver, a properly formed feed ramp.
Also differing the ORF receiver, it has a safe/semi position instead of semi/safe/auto. This requires the selector be recut as receiver semi is selector auto, disengaging the disconnector.
Muzzle brake, barrel pin, selector stop, and trigger guard rivets.
Sear assembly with semi and auto sears, as well as auto arm.
In this configuration it's 17.25mm wide, but receiver walls are 2.25mm thicker so some needs to be removed.
The auto arm also needs removal.
Sear assembly trimmed and arm removed. Now the two sears need to be tacked together to act as one.
Ejector is installed and staked in place before blast and paint.
Almost all the tan parts are now cerakoted, I forgot the trigger guard. Whoops.
Gas block and front sight repinned to barrel, with handguard retainer included, this is not to be forgotten. It's recommended that if you want to do two colors, mask it. Realigning them is a pain.
Muzzle brake needs blind pinning.
Brake is dimpled with a 3/32 inch bit, rotated, then cross drilled it provide for a larger contact area with the barrel
Brake is then screwed onto the barrel as a guide and drilled, keeping an eye on depth.
Roll pin is cut so it will be recessed inside the brake and punched in. Brake doesn't rotate when the detent pin is depressed, ready for weld.
Not pictured to avoid redundancy but completed, pin has been welded over.
Headspace gauge has been located, fairly integral for the next step of pressing the barrel on.
Bolt group was installed and headspace guage retained with the extractor and the barrel pressed on.
It was then drilled with a #25, reamed with a 5/32 and chamfered with a 3/16 on one side.
The 4mm barrel pin was started with a hammer then pressed in flush on the 12-ton shop press.
Sear assembly has been welded together so the auto sear moves with the semi-auto sear.
It could have been cut off or replaced with a spacer, but this method provides for a larger contact area on the striker.
Unlike the ORF receiver, the D-Technik receiver has the selector positions changed.
Ths czech selector has semi, safe, and auto at 270, 180, and 90 degrees, respectively.
The D-Technik receiver has safe and auto at 180 and 90 degrees respectively.
This requires that the semi notch be filled and recut 180 degrees from the original, otherwise the bolt carrier would not engage the disconnector.
The sear engagement surface was then removed for the auto arm of the trigger assembly instead of also welding up the corresponding selector notch.
The arm could have been entirely removed or the notch welded, this was simply the easiest and cleanest method.
Rivet backer for the rear trigger guard.
And another tool to span the trigger guard so the rivet could be pushed in on the shop press.
VZ.58 complete, mostly.
FCG pin retaining plate.
FCG pin retaining plate drawing.
The plate is fastened to the reveiver with a rivet through the selector stop hole and pivots at that axis.
When the pins are locked, the top edge of the plate rests just below the striker channel with the plate recessed inside the grooves on the pins.
To quickly take down the FCG, the tab on the rear is pressed, lifting the plate from the pin grooves.
The current alternate method is e-clips on the pins as the receiver is not milled wide enough to accept the Czech takedown lever.
complete with EOTech
- Test fire