Not a good range day with the Vz58's!!!

CobraGT said:
First, the compact - casing ejects, bolt carrier gets stuck partway closed while chambering next round. I look to see what has happened, and find that the gas piston has snapped in half, with part of it wedged in place above the chamber, keeping the carrier from closing!! :eek:
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Thanks for the review. I was considering buying one of these, but you have changed my mind. Sorry for your headache.
 
CSAs don't use the retaining lever Clobb...

Clobbersauras said:
Stolen from another thread...

Picture107.jpg
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They use a 'c-clip' arrangement to prevent drifting of the pins. Can't state this authoritatively for every model they crank out of course. Just the ones I own.

But you're right. He should ensure they're still in place on each pin.


You can see the machined recess that the clip captures on the rhs of he pin in your own photo Cobra:
VZ0002.jpg




On account of both guns s**tting the bed on the same day it sounds like bad Luck.

Can't even comment on the broken piston.

But the second gun might simply be a reassembly issue. You, or whoever put that NEA ambi safety in for you, might not have snapped the clips properly back into place.

Not a personal comment. Just highlighting the strong probability of human error trumping 'bad manufacture' conjecturing.

It was a pain in the ass getting them back in place on mine. Think I used a couple screwdrivers to press them in. One to provide . Another to keep the thing from constantly rotating free of the pin.

Those clips were very easy to reassemble incorrectly.


Maybe I'm wrong, and that's just fine. But if they were installed correctly and actually failed, I'd be looking for the broken fragments inside that receiver.
 
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CSA firearms in .223 sound like they are having some probs. Rods busting and also firing pins snapping in half. Oh well sounds like they are at least standing behind the product.

The second prob looks like human error. Bad install.
 
sprint said:
CSAs don't use the retaining lever Clobb... They use a 'c-clip' arrangement to prevent drifting of the pins.

But the second gun might simply be a reassembly issue. You, or whoever put that NEA ambi safety in for you, might not have snapped the clips properly back into place.
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Sprint, you're 100% correct; the guy I got the full-length Vz58 from installed the ambi safety, and I suspect he didn't push the lock plate/retaining lever back into the locked position afterward. I just didn't notice until it fell apart!

You're also right that the compact does not use the same pin-retention retaining lever, but instead uses a c-clip.

Stevo - the compact has maybe a thousand rounds through it max - probably more like 500-600


lejarretnoir said:
Thanks for the review. I was considering buying one of these, but you have changed my mind. Sorry for your headache.
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It's been a great gun up until now, but this piston issue is kind of making it look bad, isn't it??
 
Well, tagged for interest.

I'd really like to hear what can be found out about the piston failure. Thanks for posting that up.
 
Thanks for the pics. When you remove the piston on the shorty did you have to "pry" it out at all or did it come out easily?

I wonder if the bevel has anything to do with it? Maybe causing funky loads on the piston? I'm no NDT guy, but that looks pretty brittle at the break.

CobraGT said:
Haven't heard back from North Silva yet, but it's the weekend, so...

Pics of an 858 piston and the broken CSA piston below:

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CobraGT said:
Haven't heard back from North Silva yet, but it's the weekend, so...

Pics of an 858 piston and the broken CSA piston below:

Pistons003.jpg


Pistons001.jpg
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They should have never tappered the tail end of the piston on this design. Instead kept it the same length and also modified the rear cover recoil spings to take up some of the excess presure. The felt recoil would have been a little more but at least this type of stuff would have not happened.
 
Interesting - the failure looks to have been radial, in other words, a radial crack went from the outer diameter inward. Probably from multiple tiny flexures in several orientations over time.

These pistons are all used parts off military guns - there's no way to know how many rounds it saw before failure.

Is this a one-off, or have others had this issue? If a one-off, I'd chalk it up to in-service failure of an older part that might have been too hard at the high-sress revers-shoulder. A larger radius would have been a good idea in that area when designing the gun IMHO.
 
Hello

If you look closely at the break... there are two different colors..

- the outside color is silvery like the coating on the piston itself.... i'd assume that that was a crack already present when they did the coating at the factory


otherwise, unless they casehardened the piston, i don't see any other reason for the color change ( case hardened it may have a different color at the break due to the hard skin )
 
Claven2 said:
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These pistons are all used parts off military guns - there's no way to know how many rounds it saw before failure.

Is this a one-off, or have others had this issue? If a one-off, I'd chalk it up to in-service failure of an older part that might have been too hard at the high-sress revers-shoulder. A larger radius would have been a good idea in that area when designing the gun IMHO.
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The short pistons are new build for these shortys.

I've seen at least three guys here on CGN say they've had this same failure.
 
Interesting. If they are new-built, then I would say it's a design issue related to too small a radius between the shaft and flange coupled with too hard metal composition (i.e. heat treatment process refinement needed).

I doubt that is chromium in the crack. Rather, the outer cracked section looks like multiple small shear failures that reduced the diameter until the reduced cross-section failed catastrophically in a brittle plastic deformation. In other words, the part experienced tangential stress and failed in a zone of high latent stress within the part. For Grand guys, this is essentuially the same principled that led the the relief cut on op rods - a radiused shoulder is always preferable to a 90 degree transition in areas of impact stress where lateral shear comes into play.
 
According to CSA, all parts are of new manufacture.

http://www.csa.co.cz/

Czech Small Arms (C.S.A.) is the only manufacturer of the Sa vz.58 rifles and Sa vz.61 Scorpion pistols. The factory located in Jablunka, Czech Republic, continues to produce these legendary firearms for distributors in North America and in Europe.* CSA is currently the only factory in the world producing new Sa vz. 58 and Sa vz. 58 Sporter. All other companies selling Sa vz. 58 rifles or its clones only modify and refurbish old rifles from Army surplus sales. Only with CSA you can be sure that your rifle is from new production, with parts that do not have possibly tens of thousands of rounds through them.
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