CZ858/VZ58 muzzle thread pitch

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Tehoke01

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I have read on this sight that the muzzle thread on the CZ/VZ rifle is M14X1 (RH).

A machinist friend of mine cut and threaded a steel bolt/rod to that size and the CZ/VZ muzzle break threads onto it just fine and when tightened up the break holds in place solidly.

That being said, before the muzzle break is tightened up there seems to be a lot of "play" between the break's threads and the machined steel rod's threads.

My friend suggested it could be a matter of tolerances and said the threads cut into the "test" rod are M14X1 class 2. He suggests that the thread on the rifle barrel is probably a class 3 thread.

Does anyone on the boards here know the exact threading that is on the muzzle of the CZ/VZ rifle?

I really want to know because I want to use a CZ/VZ muzzle break on a modded M14.

Any help would be greatly appreciated.
 
Just a suggestion - thread the M-14 barrel with the brake at hand, and obtain the fit you want.
 
Thanks John, I'm looking forward to reading what your measurements for the threads are...

And Tiriaq, I'm thankful for any advice but I'm not really sure what your suggestion means, is it possible to explain? Thanks.
 
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Do you happen to have or have the ability to make, a bolt/threaded rod that is M14X1.0?

If so, I would be interested to know how much(if any) "play" you have between the bolt/rod and the CZ/VZ muzzle break threads before the break is fully tightened.

I got hold of an M14X1.0 tap and tried to run it by hand through the CZ muzzle break, and it got jammed about halfway. Does this mean that the muzzle break could be slightly smaller than M14, i.e. some custom size???
 
It is possible, I was talking with a friend about this though, the other possibilty is that because the spring loaded retainer pin doesnt ensure that the muzzle break is tight against a shoulder the threads could be made to an interference fit to ensure that there is no "drooping" of the muzzle break. If the original tolerance of the clearence hole was close to that of the bullet you can understand why it is important that it be true to the barrel. I will try and sneak the barrel into the shop when there is no one around and put it on the optical comparator, If I can do this I can measure the exact pitch dimension, In the mean time I finished my own break today and I am goinig to take it home tonight and try the fit and finish. I will update you as to what I find tommorow. As a last resort I can turn up a "custom" thread but there is some restriction as to what the lathe can do. If this is a whacky thread than I think I will have to get a couple taps ground and sell them on the forum!!
Cheers for now,
 
Well it could be a problem with the tap, that is possible...

...I tried it with 3 different CZ muzzle breaks and 2 muzzle thread covers and the tap seized in all of them.

When you tried your custom muzzle break on your CZ how was the thread fit? Nice and snug from start to finish or did it have a little play before tighterning it up completely?

Do you create custom external threads or do you use a die?, If you do use a die, what brand of taps and dies do you use?

Sorry if some of my phrases or ideas are not spot-on, I'm not a machinist myself, the knowledge I currently posess is little better than layman level but I'm learning as I go.

Thanks John.
 
Here is the tap I used, I was able to thread it with my fingers only? It fits very nicley through the piece. there was about a 1/2 a turn of thread that was damage\not fully threaded at the exit end of the cap. What type of Tap are you using?
 
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Aren't AK muzzles threaded 14X1 left hand thread, It would be nice if anyond had one laying around to try on a VZ :D
 
Thanks for all your help and knowledge John.

I think I'm going to have to get my buddy to recheck that threaded rod he made a second time because if you are using a regular M14X1 thread and all seems well...

...have you tried cutting a rod/bolt to M14X1 and threading your CZ break onto it?, if you do, please let me know what happens.

I don't want to have my M14 cut and threaded only to find out there's a "wiggle" when I go to put the break on:eek:.
 
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