I abandonded AKs for the most part after I got my VZ. I have two. The first one I picked up was a Century build with beaver barf. I loved it and the bonesteel muzzle brake makes it a total pussy cat to shoot. There is an old thread from way back where I showed the US made piston that got bent in the gun and I had to cut it out. Put in a surplus piston and it ran like a Swiss watch. I picked up a Czech point rifle with blonde furniture and picked up some black sythetic furniture as well. The are exceptionally pleasant rifles to shoot.
If you do buy a Century, beware of the Gremlins!
From an old AR15.com post:
In order to understand the common problem referred to as the VZ58 "gremlin" and the reason for the "tabbed" carriers, you will first need a general understanding of how the fire control group works.
how the semi auto trigger system works
When the rifle is cocked, the striker is held rearward by the sear, preventing it from sliding forward and hitting firing pin.
when the trigger is pulled, the disconnector, which is pinned to the trigger, is pulled forward. When the disconnector is pulled forward, a small protrusion on the disconnector hooks onto the bottom of the sear, and rotates the sear on its pivot. When the sear is rotated, the striker is released and slides forward to strike firing pin and fire the weapon.
When the weapon is fired, the gas system will send the bolt carrier rearward, to reload and re-cock the weapon. This happens very fast and the shooter does not have time to release the trigger during this action.
Since the trigger remains pulled, in order to return the sear to its original position, the trigger must be disconnected from the sear.
When the bolt carrier is traveling rearward, a lump on the bottom of the carrier, contacts a lump on the top of the disconnector, pushing the disconnector downward. When the disconnector is pushed downward, the protrusion that hooks the sear, is slid off of the bottom of sear, releasing sear to return to its original position, where it can catch or "cock" the striker. The hook then sits underneath the sear until the trigger is released and it can spring back up behind the sear again
The carrier then continues its rearward travel, until the end, where it reverses direction and is returned forward by the recoil spring.
On the way forward, the striker is caught by the sear which should now be in its original position. Continuing forward, the carrier then strikes the disconnector again, and continues to travel all the way forward loading the next round. The striker remains held by the sear, until the shooter releases, and re-pulls the trigger.
What the problem is and what causes it
The VZ58 "gremlin" is a condition that can result in the striker not being caught by the sear and follwing the carrier home, leaving the rifle uncocked.
The "gremlin" shows itself when for one of several reasons, the sear re-connects to the disconnector after the carrier has disconnected them during its rearward travel.
The main reason, is that during the carrier assembly's rearward travel, the striker must push the sear back down in order to corss it. If the sear is pushed down as far as it gets pulled down by the trigger, it will pass the hook on the disconnector, allowing the disconnector hook to spring back up and re-connect with striker. The only reason this does not happen everytime, is that there is a small amount of overtravel, meaning that the trigger/disconnector travel slightly farther than the sear must in order to release sear. If the rifle were to have zero overtravel, a re-connect would occur everytime. What makes it occur when there is some overtravel, is that when the sear is pushed down it ihas inertia and travels farther than the striker actually forces it. In summary, if the sears inertia outweighs the overtravel + sear spring pressure a re-connect will be caused.
The other reason can be from the shooter. Many shooters, albeit unknown to them, will actually partially release and re-pull the trigger during recoil. This action would not be noticeable if it weren't for the fact that it can, in affected vz58 rifles, exascerbate the lack of overtravel and cause the "gremiln" to appear. This explains why some shooters experience the problem more frequently, even with different rifles than others.
When a re-connect occurs during rearward travel, it stays re-connected until the carrier hits the disconnector again on the way forward, the problem is that by that time, the striker has already crossed sear and is on its way to follwing carrier home, resulting in an uncocked rifle.
What is a "tabbed" carrier and how does it fix this problem?
A "tabbed" carrier, is an original bolt carrier, that has had a tab of steel welded to it, extending the disconnector lump forward. It fixes the problem completely by extending the lump forward far enough, that during the carrier's forward travel, it will hit the disconnector before the striker crosses the sear, so even if a re-connect happens another disconnect will happen before it is too late, and the sear will be at home to catch the striker and cock the rifle.
Why don't the Czechs have this problem on the original rifles?
The original rifles have an autosear, which holds the striker rearward until the carrier finishes it's forward travel. Therefore the striker cannot follow carrier home, and by the time the autosear has released the carrier will have already disconnected the trigger from the sear allowing the sear to return to its original postion and catch the striker.
What rifles come with "tabbed" carriers?
All D-Technik/Czech Small Arms rifles
some early century rifles.
I believe CSA(Czech Small Arms) has a patent protecting rifles with "tabbed" carriers
There are a lot of rifles out there without "tabbed" carriers how important can it really be?
How important is it that your rifle always goes bang?
Although the problem is sometimes infrequent it is always there and can manifest at any time, most likely when it will huirt the most.
It can be made even less frequent by increasing overtravel and or sear spring pressure, but both of those solutions are detrimental to trigger feel and neither completely solves the issue.