CZ858 piston issues/takedown

K

KRASHED

CGN Regular
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Location
Central Ontario
Hi all,

On my third CZ858 and have never had issues with takedown or firing before.

Took the 858 out a couple days ago and the piston would not fully retreat into pre-firing position after each shot. This caused the bolt to not fully close.

Figured it could be a cleaning issue so I field stripped it and now I can't remove the bloody piston.

I pull the piston back towards the rear of the weapon as per the manual and numerous youtube videos but it doesn't budge more than a milometer.

Really frustrated, please help!
 
I was wondering the same. OP do you have any spares that you could try as an exercise in eliminating possibilities?
 
I would either contact a gunsmith or take a hammer and knock the piston forward and then see if I could pull it back again like normal. That's really risky and probably not worth it but what can I say, I live dangerously ;)

I have no real idea what could've caused this...maybe the gas port got blowed up and there's metal protruding into the regular resting spot for the piston? Either way spray it down with some lube before trying anything.
 
Got an answer from the gunsmith. Apologies if my terminology is off but here's what's wrong.

I've put probably 100-150 rounds through it and it worked no issue. At some point though when the bolt pushed the piston forward to pre-firing position the front end of the rod wasn't lined up perfectly with the housing. When the rod slammed forward it damaged the edge of the housing causing a burr which in turn rubs on the piston.

The piston can be knocked back and forth with a slight tap of a hammer and punch.

Kinda sucks. Don't know what to do. I was part of the March purchase in the last batch from Wolverine. Is there a warranty?
 
could you not cut the piston right at the gas port, then get a very small fine dremel bit to take out the burr as I assume its pretty close to the out side and then buy a replacement piston?
 
I think there is a warranty. Just call them.
Also post picture of the place where there damage of the edge is. Depending on the place it could be totally safe to file it down.
 
I've got an extra piston if that would be of any help? I assume they haven't changed, mine was bought 4-5 years ago. PM me if you want.
 
Forgot to add, the piston can be removed by using a punch and hammer so I don't need another one but thank you.

Just don't want to possibly ruin it by using a dremel and possibly having some sort of leak around the cylinder. Will contact wolverine.

Thanks all
 
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