VZ52 Piston Work (Update to:Vz-52 she not ejecting)

[skrypnyk]

Ok, so here is the original video of me shooting.

http://www.youtube.com/watch?v=uDHYB0xuAls&feature=g-upl

Then watch these two videos of what I did today, lots of hammering, grinding (never what a guy wants to do to a rifle) but I think I fixed these issues,

Watch the two videos,

Once again thanks for all the help, the advice sorted me out 100% today.

Action in a vice, just completed a bunch of work, it seems to be sliding again,

http://www.youtube.com/watch?v=EA4_7KgyN0U&list=UUVorEUAZslrzIP20wF-2VTg&index=1&feature=plcp


Action re-assembled, and seems to be working great now.

http://www.youtube.com/watch?v=j65Y53gvv7I&feature=g-upl


And before you flame me for not understanding 100% the complete operating mechanism of this rifle, remember that just two weeks ago I did not even know what it was...

so ya

 

[stickhunter]

I took the handguard off but I honestly have not clue how this weapon operates ( I know it drives back on somthing but I see no piston rod, and no real gas tube or anything like that..

anyways, any tips?

I'm going to guess that you have a bit of corrosion or carbon buildup which has seized your piston.

When you take the handguard off, you'll see a piece of sheet metal, about 6" long, which wraps around the top of the barrel; this is the operating "rod". With the bolt locked back (without a magazine, you'll have to reach into the mag well with your finger and push the bolt catch up), you should be able to move the oprod back and forth 3/8" or so into the receiver. As you do this, you'll see the oprod bearing against a spring loaded piece with two fingers that rides into the receiver --- this is what engages the bolt and drives it back.

Push the oprod into the receiver and then tilt the opposite end up to remove the oprod. The opposite end fits into a shallow lip on the piston. The piston is a ring of metal about 2" long, which surrounds the barrel. Under the piston is the gas port. With the oprod removed (and even with it attached), you should be able to grasp the piston and move it towards the receiver.

Since the gas port is under the piston, rust from corrosive ammo can form and seize the piston. If the piston is not free to move, try a few drops of oil and let it sit for a bit. You can also *carefully* use a brass punch to try and nudge the piston forward. Be careful not to damage the surface of the barrel on which the piston rides --- the barrel's surface are the "cylinder" walls that seal against the piston.

If the piston is freely moving with the oprod attached, but your rifle is still not ejecting, let us know.

Here's a picture showing the piston (left) and oprod (center):

Here's another picture showing the two parts that comprise the piston. Corrosion can form between the inner ring (left) and outer cup (right), as well as between the outer cup and its bearing surface on the barrel. A brass punch, lightly tapped against the edge of the outer cup, may help move it off of the inner ring.

 

[Andy]

Nice to see someone shooting one of these.

You should certainly thoroughly clean the firearm, but there are other possible causes for poor extraction such as the ammo. I assume it's surplus, but it might be have become weaker due to poor storage conditions.

Mags can also cause extraction problems, but you don't have one. Mags for the VZ-52 are not so rare, unlike those for the VZ-52/57. I have one for the VZ-52 that I could possibly be convinced to sell.

 

[Innercity]

Do what Stick said and then clean the Chamber, I had a similer problem with my 52/57 the first time i took it out. It looked spotless but ther was lacquer build up in the chamber from the surplus ammo causing the cases to stick.

 

[skrypnyk]

Thanks guys, I will do these fixes and advise on results.

Stickhunter, I appreciate the work you put into your response, seriously thank you.

 

[skrypnyk]

K, I did a bunch of work today, I changed the info on the top and uploaded a couple videos to Youtube. They describe what I had to do, and how its working now.

 

[stickhunter]

K, I did a bunch of work today, I changed the info on the top and uploaded a couple videos to Youtube. They describe what I had to do, and how its working now.

Glad to see you've got the piston moving freely, and hopefully the chisel and dremel work haven't damaged the seal too badly. I've got to say, I cringed a bit when I listened to you describe what you had to do to free the piston --- the bearing surface of the piston has tight tolerances, so you really want to be gentle around it. What's done is done, so as long as you clean the rifle properly after firing corrosive (and I believe all surplus 7.62x45 is corrosive), the piston should remain free.

Since you also pulled off the lock nut, you should follow these directions when reassembling to make sure the gas system applies the proper force to the bolt. When properly adjusted, the brass should fling forward and to the left of the action (opposite to most semi autos), probably 6-8 feet away.

Gas System Assembly. Slide the drive spring down the barrel into it's recess on the receiver. Follow with the drive spring plunger, aligned so it's two arms will fit into the receiver . Follow with the gas piston, small end toward receiver. Thread the actuator onto the barrel slightly past the point where there will be room for the actuator lock nut. Thread the lock nut onto the barrel until it is aligned with the first barrel thread. Unscrew the actuator until it stops against the lock nut. The lock nut uses a 22mm wrench, the actuator a 23mm wrench. Not having a torque-specification, the best recommendation I can make is "snug."

Operating pressure can be adjusted by first loosening a jam nut in front of the gas stop with an armorer's wrench. If the gas stop is then screwed toward the breech (again, with the armorer's wrench) the expansion chamber's volume will be reduced and the pressure will be increased to operate the system under adverse or fouled conditions.

If the gas stop is screwed toward the muzzle, the expansion chamber's volume will be increased and the operating pressure will go down, reducing the violence with which the components act upon each other.

Unfortunately, there are no markings to indicate relative positions of adjustment. Adjustment is thus always by tedious trial and error only. To complicate matters even further, there is an infinity of positions between fully opened and fully closed.

That might be acceptable, but the average Third World soldier cannot handle the concept of "infinity," which he probably believes to be an obscure branch of the infantry. Everyone would have been better served with very large, single-digit numbers deeply etched into the gas regulator.

These two quotes from from the following links:
http://www.arizonaresponsesystems.com/notes/notesmisc/vz52/pagevz52.shtml

http://www.thefreelibrary.com/Czech+Vz52.-a0197408972

 

[skrypnyk]

So I did a kind of test I though of to test the seal of the piston, I filled up the sliding piston end with as much WD40 as it would seem to hold, I then tried to press it into the closed position. it would move only very slowly (as fluid drained into the gas port and into the barrel) none seemed to be pushed out the top seal end.

so it still has a seal. I was really just trying to "de-bur" the inside edge of the piston head. I only scraped the burs, I did not just grind away on the entire inside. Believe me I was not happy about what I had to do, but I was hammering all sides for at least 20min. This thing was not going anywhere. I used penetrating oil, and break away, and everything else under the sun. Believe me this was a last resort.

but thanks I will make sure I adjust the locking nut correctly.

 

[svt1940]

So I did a kind of test I though of to test the seal of the piston, I filled up the sliding piston end with as much WD40 as it would seem to hold, I then tried to press it into the closed position. it would move only very slowly (as fluid drained into the gas port and into the barrel) none seemed to be pushed out the top seal end.

so it still has a seal. I was really just trying to "de-bur" the inside edge of the piston head. I only scraped the burs, I did not just grind away on the entire inside. Believe me I was not happy about what I had to do, but I was hammering all sides for at least 20min. This thing was not going anywhere. I used penetrating oil, and break away, and everything else under the sun. Believe me this was a last resort.

but thanks I will make sure I adjust the locking nut correctly.

Glad that you unstock your piston. A brass punch or a brass hammer is helpful in this kind of situation, can avoid dammage. Also applying some heat on the piston with a propane torch could have made thing easier
Joce