Century VZ2008 Gas Piston Issue

[dakota.potts]

I've had my VZ2008 for about 2 and a half years, shot probably 1,000 rounds or more out of it, and so far haven't had any complaints.

Takedown has always been somewhat difficult with the gas piston. It's been prone to binding when being removed and always took some effort, although lately the issue has gotten worse.

I took it down for a thorough cleaning today and realized it was really hard to remove the gas piston. To the point I had to use tools to help me remove it at one point when it bound really bad.

I watched some other takedown videos and noticed first of all that I don't have a gas piston return spring! I don't know when that happened or how long I've been running without one, but it hasn't impeded function I have heard of them corroding but I imagine I would have found something left of it if that had happened, and I don't shoot particularly corrosive ammo (mostly Tula and Barnaul).

Anyways, the real issue seems to be that the piston is bent. After putting some heavy solvent and scrubbing the gas tube and the rear sight base where the piston rests, I put a very healthy coating of Rem Oil where the piston rides and on both contacting ends of the piston. I had some trouble getting the piston back in, but when rotated a certain way it will go into position more easily. Once into position, I noticed it was still binding. With some experimentation, I noticed that when turned to one orientation it glides so smoothly that I can move it back and forth with just my pinky. Turned 180 degrees, it binds enough that I need a full grip with two hands to move it back and forth. This tells me it's bent somewhere in the middle. I don't want to keep shooting it like this, as I imagine that will end up putting uneven pressure on the rod and warping it more.

Curious if anybody has had this problem. I read about it on other forums and it tends to usually be an issue with US pistons being soft. I may have to order a new one, but I'll also have to look into the 922(r) parts count to see if an original part would put me over the parts limit. They have a reputation for being of a better quality.

I'll also end up replacing the piston return spring with a new one. There are some new production models that are supposed to be better metal and chrome plated for longer life and corrosion resistance. Will have to look into it for a few dollars more.

 

[marine6680]

It could be that without the spring, that it is moving rearward too far and too quickly, and that may be causing the warping.

Century may be able to send you a new piston.

 

[dakota.potts]

I wondered if the lack of the spring might be contributing. I haven't the faintest idea how long I've been without that spring but I don't remember having a spring there any one of the last times I've disassembled it and that's several hundred rounds at least.

I'll call century but I think any warranty they had is long gone.

 

[HankC1]

VZ2008 bent piston rod is a known issue due to heat treat issue, some said it has been corrected in later build. I have a VZ2008 bought 2 yrs ago, haven't seen it yet but my round count is still low. Surplus piston costs around $20.

 

[marine6680]

Is the piston even on the list of 922 parts?

 

[dakota.potts]

I know in some guns, the piston is considered the "op rod" which oddly enough is the charging handle on the HK series of guns... I'm sure the ATF has a list somewhere of what VZ58 parts count as what on the 922(r) list but I always thought the piston was one of them.

So far the issue hasn't resulted in a single firing malfunction but I see it now as being a potential hazard to causing more damage so I'm going to look for a replacement before I shoot it again.

 

[armoredman]

Oddly enough I have an old vz-58 gas piston rod sitting around doing nothing. Wonder if it would fit.

 

[dakota.potts]

The Century guns are built on Czech parts kits so I don't see any reason it wouldn't fit if they located their gas hole/port at the right place

 

[armoredman]

It's the original, replaced it with an American made part a while ago. Dirty.

 

[Pond James Pond]

With some experimentation, I noticed that when turned to one orientation it glides so smoothly that I can move it back and forth with just my pinky. Turned 180 degrees, it binds enough that I need a full grip with two hands to move it back and forth.

Does this mean that you might be wearing an eccentric bore in the piston port?

 

[dakota.potts]

I doubt that I'd be contributing much to any undue wear in the gas port. All contact will contribute to wear, obviously, and eccentricity will tend to increase the wear but I'm more concerned with what it's doing to the gas piston to shoot it in that condition.

 

[chris in va]

I built a Saiga conversion a few years ago.

Let's be frank on this, we all want to be 'legal' with 922, but worrying about a US made gas piston is absurdly low on the ATF's radar.

 

[bodrika]

The gas piston in your VZ2008 may be bent, especially if you didn't have a spring, but it may very well be fine. I have three VZ2008's and replaced the gas pistons with military surplus ones, mainly due to reports of the Century US-made pistons bending. What I found, however, is that the holes in the rear sight blocks where the piston exits to hit the carrier are much smaller on the VZ2008's than on the original VZ58's. The holes are not only smaller, but of slightly different sizes among my three VZ2008's.

I found this out as the surplus gas pistons would bind when rotated. Also, I have an original VZ58 surplus rear sight block/barrel and the gas piston hole in that is much larger than in any of my VZ2008's. I then inspected the surplus gas pistons I have and while they are all in great shape, none are perfectly true -- and they probably don't have to be. There are very slight contours along the tails and heads. I believe this to be normal. My three Century gas pistons and the several surplus ones all have slightly different diameters and dimensions from each other. This I also believe to be normal. The larger hole in the surplus sight block is likely to be built-in slop to accommodate varying manufacturing specs spanning different decades and different armories. That surplus sight block has no signs of being tampered with or the hole enlarged.

Which leads to the remedy: I took a round file and very gently opened up the rear sight block holes on my three VZ2008's. It didn't take much and they are still slightly smaller than the hole in my surplus sight block. Go easy and R&R until your gas piston articulates in any rotated position.

I'm sure a spring will help. I've never fired mine without one, and I'm surprised it actually functioned at all. A surplus gas piston is also a good idea as not only are they likely to be sturdier, they are chromed and easier to clean. It will be a 922r consideration, and I agree the concern is probably very low, but that can be solved by changing out the hand guards, the stock, or the pistol grip. CNC Warrior used to have a US-made gas piston for sale, but they've been out of stock for months.

Good luck.