Belom tactical 7.62x39 in SZ-527 American?

[Wibo835]

Hi all,

I ordered some Belom tactical 7.62x39 ammo and tested it in my CZ 527 American rifle.
6 rounds did not bang out of 20 in the first box.
I see very good feedback at the site where I ordered the ammo from, so I feel confused what could be wrong with my rifle.

The rifle shoot very well all steel cased ammo I tried (Tula/Barnaul/Wolf) and all my reloaded brass with CCI primers, never misfired.

Any thoughts?

Kind regards,

[david s]

If the rifles been reliable in the past and the only new variation is the Belom ammo I would be inclined to begin my search for an answer with the ammo. What do the primers look like on the six round that didn't fire? Have they been hit hard enough that the rounds should have fired? And on the Belom ammo that fired how do the primer strikes compare to the primer strikes on the non Belom ammo that fired look? It hasn't been my experience and I do have a CZ 7.62 Carbine, but others have had problems with failures to fire with certain brands of ammo in the CZ Carbines. It's common enough that two companies sell heavier firing pin springs for these rifles. But I'd begin my search for answers with the new variable first.

[alp3367]

 I tend to agree with everything David S said. If it shoots everything else well I'd suspect the ammo. Though looking at the fp strikes on the primer would be one of the first things I did. If possible, I'd try to both fire it again in the 527 (if you hadn't) and also try it in another rifle.

[sign216]

Can you attach a photo of one of the spent primers?  I'd like to see the pin strike myself.

[crosstimbers]

Yeah, if it has shot everything else without problems, it's not the rifle. I've never used the ammunition you mention though, so I can't comment further.

[Wibo835]

Sorry.
I cannot upload the photos. 

[Wibo835]

The picture of another brand failed in my CZ 527 (2 of 20 failed). This is Berdan primed ammo.
Two on the left failed, one on the right fired:



https://imgur.com/a/UMA6aV8

[crosstimbers]

Hmmm, well the two on the left don't necessarily look like light strikes to me. So, I'm still inclined to blame the ammunition. Of course a pic posted online isn't the same as seeing it up close.

I'm assuming being Berdan primed that it's foreign made?

[sign216]

Although the two left ones aren't classic "light strikes" they do appear to be lighter hits than the right one, which fired.

Who is selling the stronger firing pin springs?  Any downside to fitting them, like harsher trigger pull etc?

[david s]

Just looking at the primer strikes I would have guessed the two on the left should have fired. J&P Custom Products and Numrich both offer striker springs for the 7.62X39 CZ 527's. I've not used them though.

[sign216]

David, thanks for the lead.  Numrich offers two diff 527 springs:

STRIKER SPRING, 3.5" OAL, NEW FACTORY ORIGINAL
STRIKER SPRING, 7.62 X 39, 4.58" OAL, NEW FACTORY ORIGINAL

Both are called "factory original.  The 7.62 spring is longer.  Did the factory change the 7.62 spring to deal with the oddities of various military ammo?

JP Gunsprings also has a 527 striker spring.  They don't give the length.  They imply it's the same length as factory, but of improved chrome silicon, while the factory spring is music wire.  JP implies their spring is stronger, and gives more consistent ignition. 

Joe

[david s]

Never used either spring in my CZ's so can't say. I didn't even notice the different length of the Numrich springs only the doubled cost of the 7.62 spring. I don't know if CZ ever changed the 7.62 springs and if they did what their reason was. That might best be answered by CZ-USA. Some others have had a miss fire issue with their 527 rifles in the past is about the extent of my knowledge on this. There are a couple of earlier threads on the forum about this. I'm fortunate that my 527's haven't had miss fire problems. My experience with this issue involved a Browning 71 in 348 Winchester.

[sign216]

David, thanks for the update.  I'll search some early threads, and probably buy the JP spring, since their write up sounds good.
It's a cheap upgrade.

[sign216]

I looked at earlier posts, and dragged up a comment from CZ: 

"Built to CIP specifications, our 7.62×39 chambers are ideal for shooting steel-cased surplus ammo. Designed to shoot .311 bullets, some American brass ammo may not perform as well as the imported steel-cased variety because of SAAMI brass dimensions and varying bullet diameters."

Old posts did show some problems w brass cases ammo, even ones loaded to CIP specs, like the orig poster of instant thread.

Here's a list of some of the fixes:

1.  Stronger springs from Gunpartscorp or JP Gunsprings helped some, but did not help others.

2. In the past some people got longer firing pins from CZ, or had a machinist make them. 

3. Two people put bushings behind the orig spring to increase tension.  One made it out of a "high collar lock washer" the other used scrap metal.  If you take up too much of the free coil space it may be a problem.

4. Some gently stoned (sanded) a "stop" on the pin body, see link below:
https://czfirearms.us/index.php?topic=50455.0 

5.  Handloaders reported that neck sizing only helped the problem.  And/or switching to a softer brand of primer.

6.  One reported rough machining in the firing pin channel, but others said their channel was smooth. 

So, those are some tips to try out.  Please let me know what works for you.

Joe


Here are instructions on replacing the spring:
Do not drive out the pin. Instead, rotate the bolt sleeve (black knob on back of bolt) a 1/4 turn counter clockwise, to un-cock
the bolt(firing pin should protrude from the bolt face). In this mode the bolt handle will now be free to pull out of the bolt body.
With the handle removed, the striker assembly will now be free to come out to the rear. The striker spring is retained by the silver keeper on the end of the assembly. Pulling the keeper slightly to the rear, and rotating it a 1/4 turn in either direction will release the spring. Note: The keeper is under heavy spring pressure. Be careful not to lose the keeper. Assemble new spring in reverse order.

Use a large vise and a 6mm (1/4" drive) deepwell socket to reassemble.

[david s]

The firing pin assemblies come apart fairly easily with everything under spring pressure so keep things contained and let the spring decompress slowly. The biggest problem with these is in the reassembly. The 'sliver keeper" spring retainer has a square cut hole thru the center that corresponds its similar shaped retainer ledge on the firing pin, The tolerances are tight and getting everything lined up just so while compressing the spring can be a pain in the elbow. Try a couple of springless reassembly dry runs so you get a feel for how everything fits and then try it with the spring added. By no means impossible but it can be a pain on occasion.