MythBusters
m39a2 said:
They are perhaps the most overbuilt rifle ever! Far heavier than required in every respect than required for the cartridge. It uses the fire control system of a Garand/M-14 and I'm not sure if the gas system is home grown or not but it is unique. It even has an adjustable gas system but you have to take apart the whole rifle and use a big wrench to do the adjustment. Try to stay away from corossive ammo if you can, the gas cylinder is a pain to clean!!
Scott
Myth: "The VZ-52/57's gas system is a ##### to clean"
Reality: It is very simple
IF YOU ARE FAMILIAR WITH IT 
The gas system is one of the reasons that rifle is so accurate: it is concentric with the barrel's axis and doesn't exert any torque on it when ejecting.
The other one is the rifle's adjustable bedding tension.
Cleaning it is a real snap: take the upper cover out by pressing the catches near the rear sight and pivot the cover towards the front while pulling it back a tad.
Take the magazine out, too.
Now, take a loaded round and place the tip of the bullet in the hole at the base of the bayonet blade and push while sliding the barrel retainer towards the front sight.
Once done, lift the muzzle of the rifle up and all the rifle's mechanism will lift out of the stock.
Put the magazine back in the action and lock the carrier to the rear.
Push back the small tubular piston at the front, hold the U shaped channel that connects the annular piston and the secondary actuator (the part that pushes on each side of the bolt carrier) and separate the piston and the channel. The piston is now free to slide down the barrel and you can clean around it. Scrape the inside lip of the piston and pass a Q-tip saturated with nitro powder solvent in it.
Wipe the steel U shaped connector and all these parts and you're done. See? Easy!
Note: In front of the piston and gas hole, there is a ring bolt with another behind it. This bolt regulates the gas chamber volume and thus the push on the piston; the other one is the adjustment locking bolt.
Now for the trigger block:
Get the magazine out and release the bolt carrier.
The trigger assembly can be taken out of the action ONLY IF
1) hammer is cocked
2) safety is on.
With a large screwdriver, put some rearward pressure on the spring steel trigger guard near the base. There is a catch there that will allow the trigger guard to swing down forward when released; it is quite stiff.
Once released, push it all the way and the whole trigger/hammer mechanism will slide forward and out off its lugs. Clean it by dunking in a solvent or with a blast of Rem-Clean.
Get the receiver cover out: put the barrel in a vise with a protective padding. You need both hands for the rest.
With dry hands push on the receiver cover forward against the recoil spring. Once it is in front, it can be disengaged from the receiver races and CAREFULLY lifted at the rear, just to clear the receiver's rear abutment. Don't lose grip of the cover now as it will fly out with much force! Be careful not to kink the spring.
Take it out and avoid separating the spring assembly.
Now, you may slide the carrier and bolt to the rear and remove it. It works best when the barrel and receiver assembly is upside down: just hold the assembly in your hand and it will clear the race lugs at one point and fall in your palm.
Clean and lube everything and reassemble. A complete bolt stripping is possible without any hammering but I'll let you find out for yourself: it is so clever and so nicely machined that it is a pleasure to explore.
Remember: never force anything, it is not necessary. Be careful not to lose the ejector spring and the firing pin spring too.
BTW, one day, if I find time for it, I'll do a complete How-to with pictures on this one and post it here and in the Milsurp.com's site.
Have fun!
PP.
