Courtesy of our friendly legal counsel:
Disclaimer:
Modifications made to this pistol were performed by an experienced professional airgunsmith.
And, proved safe in THIS gun.
No warranties are implied nor extended.
We have no control of what you do on your own.
If you do decide to make ANY modification to an airgun, be conscious of which elements are under force or pressure and realize that, even a "little pre-compression" or as little as 10 BAR's CAN cause SERIOUS bodily harm.
Again: Be careful! You are the only guardian of your health and safety.
Disclaimer:
Modifications made to this pistol were performed by an experienced professional airgunsmith.
And, proved safe in THIS gun.
No warranties are implied nor extended.
We have no control of what you do on your own.
If you do decide to make ANY modification to an airgun, be conscious of which elements are under force or pressure and realize that, even a "little pre-compression" or as little as 10 BAR's CAN cause SERIOUS bodily harm.
Again: Be careful! You are the only guardian of your health and safety.
Among the many things that CZ has built at the plant in Brno, now in the Czech Republic, or Czechia under the current map naming convention, I am sure there are rarer things than the ZVP.
The ZVP had a relatively short life (1960 to 1970), being superseded by newer/more sophisticated models.
Reputedly, most of the 150k specimens built were sold to the USA.... go figure.
Now, being "un-sophisticated" is not necessarily bad, it's simply a historical fact.
In the case of the ZVP, being unsophisticated, does NOT mean being coarse, or unrefined.
It is, as a matter of fact, a VERY well made pistol.
Well made, of solid materials and simple design, everyone says they are "built like a tank", but I don't agree. Yes they are solid, and robust, and somewhat "thick around the waist" if you catch my drift. But they are well made, nicely finished; like a simple, hardworking, honest to goodness, country girl.
A few shooters have reported MV's in the 350's (fps), with some undefined pellet, I found that, without dieseling, they can come close, but they are not powerhouses.
And here comes the trick question:
¿How can you run a leather sealed airgun without some dieseling?
Well, the answer lies in two aspects:
1.- The lube you choose needs to have a very high flash point because, to "diesel" the liquid needs to be vaporized and then ignited under pressure to close the "Diesel cycle". So, making sure the leather seal works with modern, high flashpoint lubricants is one aspect. Before we move forward, I have to say that I STRONGLY disadvise trying to use Silicone based synthetic olis. It is almost impossible to really find out what "silicone" is in there, and some silicones will degrade molecularly under pressure and heat (both conditions available in a spring-piston airgun's compression chamber) into Silica and its oxides, both are well known abrasives. So, USE TEFLON or Hydrotreated petroleum distillates based lubricants, mixed with natural lubricants in any re-build / resurrection project.
2.- The second aspect is a powerplant design that ensures maximal energy transfer in a very short barrel.
ZVP's barrels are 7¼" long and the stroke is barely 2½" in a 1" chamber bore (approx). So, the powerplant needs to deliver a fast de-compression of the spring and MUST keep all elements in line, avoiding chatter and all the energy losses that come from out of line movements.
To take down a ZVP, I would recommend making a "holding tool".
The ZVP is too short for most spring compressors and it DOES have a substantial amount of pre-load.
So, unless you have a personal assistant, or have three hands, it is best to create a specialized "vise" to hold the action for disassembly, repairs, assemblies and tests.
It is nothing too complicated to make, just two blocks of wood that can hold the rear end while you unscrew the action-closing cap in a solid enough manner that noting goes amiss.
So this is what I made:
The ZVP had a relatively short life (1960 to 1970), being superseded by newer/more sophisticated models.
Reputedly, most of the 150k specimens built were sold to the USA.... go figure.
Now, being "un-sophisticated" is not necessarily bad, it's simply a historical fact.
In the case of the ZVP, being unsophisticated, does NOT mean being coarse, or unrefined.
It is, as a matter of fact, a VERY well made pistol.
Well made, of solid materials and simple design, everyone says they are "built like a tank", but I don't agree. Yes they are solid, and robust, and somewhat "thick around the waist" if you catch my drift. But they are well made, nicely finished; like a simple, hardworking, honest to goodness, country girl.
A few shooters have reported MV's in the 350's (fps), with some undefined pellet, I found that, without dieseling, they can come close, but they are not powerhouses.
And here comes the trick question:
¿How can you run a leather sealed airgun without some dieseling?
Well, the answer lies in two aspects:
1.- The lube you choose needs to have a very high flash point because, to "diesel" the liquid needs to be vaporized and then ignited under pressure to close the "Diesel cycle". So, making sure the leather seal works with modern, high flashpoint lubricants is one aspect. Before we move forward, I have to say that I STRONGLY disadvise trying to use Silicone based synthetic olis. It is almost impossible to really find out what "silicone" is in there, and some silicones will degrade molecularly under pressure and heat (both conditions available in a spring-piston airgun's compression chamber) into Silica and its oxides, both are well known abrasives. So, USE TEFLON or Hydrotreated petroleum distillates based lubricants, mixed with natural lubricants in any re-build / resurrection project.
2.- The second aspect is a powerplant design that ensures maximal energy transfer in a very short barrel.
ZVP's barrels are 7¼" long and the stroke is barely 2½" in a 1" chamber bore (approx). So, the powerplant needs to deliver a fast de-compression of the spring and MUST keep all elements in line, avoiding chatter and all the energy losses that come from out of line movements.
To take down a ZVP, I would recommend making a "holding tool".
The ZVP is too short for most spring compressors and it DOES have a substantial amount of pre-load.
So, unless you have a personal assistant, or have three hands, it is best to create a specialized "vise" to hold the action for disassembly, repairs, assemblies and tests.
It is nothing too complicated to make, just two blocks of wood that can hold the rear end while you unscrew the action-closing cap in a solid enough manner that noting goes amiss.
So this is what I made:
The holding block was made using two blocks of wood, then drilled at the center and then a boring bar-turned fly-cutter was used to reach the right diameter
The bore in the holder should be only 1.5-2 mm's smaller than the ZVP's cap.
The disassembly itself is fairly straightforward.
Start by removing the grips side-screws, use a properly fitting screwdriver. NOTHING says more about a quality, well-cared gun than perfect screw slots.
Then you will need to remove the grip slotted nut.
The disassembly itself is fairly straightforward.
Start by removing the grips side-screws, use a properly fitting screwdriver. NOTHING says more about a quality, well-cared gun than perfect screw slots.
Then you will need to remove the grip slotted nut.
Use the proper screwdriver! Using pliers or knocking the nut with a chisel sideways is NOT the way to treat a gentle lady like the ZVP.
Then you will need to remove the trigger guard screw. Again use the proper screwdriver.
That should allow you to pull the action out of the grips.
Now, it is time to disassemble the action itself.
Then you will need to remove the trigger guard screw. Again use the proper screwdriver.
That should allow you to pull the action out of the grips.
Now, it is time to disassemble the action itself.
Be careful with a very, very, small screw at the bottom of the cap.
That very small screw locks the cap in place by diving into a slot, and needs to be undone before attempting to disassemble the pistol's action.
Hold the cap in the holder and slowly turn the gun.
Keep control of the gun at all times because there is quite a pre-load in the spring.
Once you have reached the end of the threads in the cap, then the powerplant can come out:
That very small screw locks the cap in place by diving into a slot, and needs to be undone before attempting to disassemble the pistol's action.
Hold the cap in the holder and slowly turn the gun.
Keep control of the gun at all times because there is quite a pre-load in the spring.
Once you have reached the end of the threads in the cap, then the powerplant can come out:
The inside of the cap has a recess where the guide's thrust washer fits.
Once the spring and guide has come out, you can disengage the barrel from the action by removing the locking screw and the axle screw.
In my "patient" the previous users had tightened too much the forks, so I had to make a shim from 0.002" Stainless steel material. Working with VERY thin material is a challenge, LOL!
Once the spring and guide has come out, you can disengage the barrel from the action by removing the locking screw and the axle screw.
In my "patient" the previous users had tightened too much the forks, so I had to make a shim from 0.002" Stainless steel material. Working with VERY thin material is a challenge, LOL!
With the barrel disengaged, the pins that hold the trigger and the sear can come out. Remember to ALWAYS drift pins from left to right.
With the trigger guard's pin driven out and the trigger and sear out of the way, the cocking linkage can be lifted from the piston's body, the barrel/cocking linkage assembly can be removed, and the piston can be extracted.
Checking the seal, it was not bad at all:
With the trigger guard's pin driven out and the trigger and sear out of the way, the cocking linkage can be lifted from the piston's body, the barrel/cocking linkage assembly can be removed, and the piston can be extracted.
Checking the seal, it was not bad at all:
It was a bit dry and needed some cleaning, but apart from that I judged it to be in serviceable condition.
What was NOT in serviceable condition was the compression chamber:
What was NOT in serviceable condition was the compression chamber:
The crud of the centuries!
With some Brake Cleaner, plus some Thinner, Acetone, and then "Simple Green", we got to the bottom :
With some Brake Cleaner, plus some Thinner, Acetone, and then "Simple Green", we got to the bottom :
I still wasn't satrisfied, so I put together a "bottom sanding bar" put some green Scotch Brite on it and polished the face of the compression chamber.
It was time to setup the piston for a resurrection:
It was time to setup the piston for a resurrection:
The liquid is a 50-50 mixture of Neatsfoot oil and Kobalt Synthetic Air Tool Oil. According to the MSDS, there is no silicones in this oil, and has a high flashpoint (> 350 °F) and an even higher auto-ignition point..Neatsfoot oil is fairly common, just try to get something that has no additives.
The piston stayed in there for 3 days. After which it was cleaned, polished and a new guide system was designed for the piston.
Here is a comparison of the old and the new:
The piston stayed in there for 3 days. After which it was cleaned, polished and a new guide system was designed for the piston.
Here is a comparison of the old and the new:
On the old version, the spring has space enough to buckle a little and vibrate, on the new system, the rear guide prevents vibration, while the forward tophat / telescoping portion of the guide grabs the front end of the spring and centers it in the piston.
As the two guides telescope into each other, with the closest possible tolerances, there is no room for the piston or spring to vibrate or chatter during the spring's decompression / Chamber compression cycle.
This is how the spring now enters into the piston:
As the two guides telescope into each other, with the closest possible tolerances, there is no room for the piston or spring to vibrate or chatter during the spring's decompression / Chamber compression cycle.
This is how the spring now enters into the piston:
The re-assembly is just the reverse order.
I am going to replace the pins for spring-pins. At this size (3 mm's) the spring pins are solid enough for the duty performed and they will remain straight, as opposed to the OEM pins that always end up crooked.
Once everyting is said and done, the gun is performing within the original specs:
JSB 7.33 Match.- 297 ± 3 fps
RWS Hobby.- 312 ± 6 fps
RWS Diabolo Basic.- 303 ± 4 fps
H&N Excite 335 ± 3 fps
Hopefully, this gun will keep on shooting for its next 60 years.
;-)
Keep well and shoot straight!
HM
I am going to replace the pins for spring-pins. At this size (3 mm's) the spring pins are solid enough for the duty performed and they will remain straight, as opposed to the OEM pins that always end up crooked.
Once everyting is said and done, the gun is performing within the original specs:
JSB 7.33 Match.- 297 ± 3 fps
RWS Hobby.- 312 ± 6 fps
RWS Diabolo Basic.- 303 ± 4 fps
H&N Excite 335 ± 3 fps
Hopefully, this gun will keep on shooting for its next 60 years.
;-)
Keep well and shoot straight!
HM
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