Bren 2 9" FTE/Stovepipe issues

[shineboy2000]

Ah the age old debate, power of 5.56 vs 7.62....

Not much to debate if you've ever shot them, or even looked at ballistics tables (muzzle energy, etc.). Barrier penetration is one that 7.62x39 clearly excels at compared to 5.56.

Oh its a very old debate, where one looses the other wins and vice versa. They hold about the grains of powder, 5.56 greater chamber pressure, more muzzle velocity... blah blah blah. I own both. It doesn’t really matter does it

[MeatAxe]

Ah the age old debate, power of 5.56 vs 7.62....

Not much to debate if you've ever shot them, or even looked at ballistics tables (muzzle energy, etc.). Barrier penetration is one that 7.62x39 clearly excels at compared to 5.56.

Oh its a very old debate, where one looses the other wins and vice versa. They hold about the grains of powder, 5.56 greater chamber pressure, more muzzle velocity... blah blah blah. I own both. It doesn’t really matter does it

No it doesn’t matter other than the fact that these jamming issues are only occurring with 7.62x39 guns, especially after changing to aftermarket hand guards / mounting plates. 5.56 guns do not seem to be so afflicted. So what’s the difference (other than @ 200 foot pounds of muzzle energy)? 🙄

[shineboy2000]

I like the HB hand guard but holding off for a bit till all this gets sorted out.

Difference in the rounds doesn’t matter

[MeatAxe]

I like the HB hand guard but holding off for a bit till all this gets sorted out.

Difference in the rounds doesn’t matter

So how do you explain why 7.62x39 guns are jamming and 5.56 guns are not?

[czfanatic_]

I have two Bren 2's, one 11" 5.56 and one 9" 7.62.  Both have had HBI handguards on since day one.  My 5.56 has over 3500 through it with zero failures.  My 7.62 made it to almost exactly 2500 rounds before it malfunctioned.  It now will perform like the OP's once every 45 rounds or so. 

I ordered a BCM enhanced extractor spring set.  I'm gonna try that spring and see if it helps at all. 

I'll keep everyone informed. 

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[Archos]

Quick update on my 9" 7.62X39 Bren2.

Got it back on Tuesday from its 2nd trip back to CZ for frequent stovepipe issues, was told this time its due to lacquer build up in the chamber.

Finally got to the range today, 380rnds with 9 stovepipes. Even tried  the original handguard at the end of the range trip and still had 2 stovepipes in the first magazine. This time at the range I purposely did not use any lacquer coated ammo, only Wolf Polyformance FMJ and HP.

I have pictures of most malfunctions, just too tired and irritated to post them. Guess I'll contact CZ again.

[MeatAxe]

Quick update on my 9" 7.62X39 Bren2.

Got it back on Tuesday from its 2nd trip back to CZ for frequent stovepipe issues, was told this time its due to lacquer build up in the chamber.

Finally got to the range today, 380rnds with 9 stovepipes. Even tried  the original handguard at the end of the range trip and still had 2 stovepipes in the first magazine. This time at the range I purposely did not use any lacquer coated ammo, only Wolf Polyformance FMJ and HP.

I have pictures of most malfunctions, just too tired and irritated to post them. Guess I'll contact CZ again.

I have two Bren 2's, one 11" 5.56 and one 9" 7.62.  Both have had HBI handguards on since day one.  My 5.56 has over 3500 through it with zero failures.  My 7.62 made it to almost exactly 2500 rounds before it malfunctioned.  It now will perform like the OP's once every 45 rounds or so. 

I ordered a BCM enhanced extractor spring set.  I'm gonna try that spring and see if it helps at all. 

I'll keep everyone informed. 

Sent from my SM-N950U using Tapatalk

bleep, sorry you guys continue to have problems...would be interested to see if the BCM AR extractor has any effect.

Just spit balling here:

1. Have you cleaned the gas system with the CZ kit supplied tools recently?

2. Any effect changing to #2 gas regulator setting?

3. How much torque are you using on the 4 hand guard / receiver / barrel screws?

4. Are you using new or the original screws and nord lock washers?

5. How do spent shell casings look?

[czfanatic_]

Quick update on my 9" 7.62X39 Bren2.

Got it back on Tuesday from its 2nd trip back to CZ for frequent stovepipe issues, was told this time its due to lacquer build up in the chamber.

Finally got to the range today, 380rnds with 9 stovepipes. Even tried  the original handguard at the end of the range trip and still had 2 stovepipes in the first magazine. This time at the range I purposely did not use any lacquer coated ammo, only Wolf Polyformance FMJ and HP.

I have pictures of most malfunctions, just too tired and irritated to post them. Guess I'll contact CZ again.

I have two Bren 2's, one 11" 5.56 and one 9" 7.62.  Both have had HBI handguards on since day one.  My 5.56 has over 3500 through it with zero failures.  My 7.62 made it to almost exactly 2500 rounds before it malfunctioned.  It now will perform like the OP's once every 45 rounds or so. 

I ordered a BCM enhanced extractor spring set.  I'm gonna try that spring and see if it helps at all. 

I'll keep everyone informed. 

Sent from my SM-N950U using Tapatalk

bleep, sorry you guys continue to have problems...would be interested to see if the BCM AR extractor has any effect.

Just spit balling here:

1. Have you cleaned the gas system with the CZ kit supplied tools recently?

2. Any effect changing to #2 gas regulator setting?

3. How much torque are you using on the 4 hand guard / receiver / barrel screws?

4. Are you using new or the original screws and nord lock washers?

5. How do spent shell casings look?

1.  Yes, I recently thoroughly cleaned the entire gas system using the provided tools.

2.  Haven't tried this setting, as I think it has too much gas already, but will try it.

3.  70 in/lbs, haven't touched them since I installed it.

4.  Using HBI provided screws with factory nord lock washers. 

5.  The case mouths are slightly "D" shaped but nothing too crazy.  The case rims don't show excessive marking.



The BCM extractor spring is out for delivery, I'll let you guys know later today if:

1.  It fits
2.  It helps / hurts the issue



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[czfanatic_]

Hey guys,

I'm getting ready to head out to the range and test out my theory with the BCM enhanced extractor spring.  I am attaching a picture of the two springs, with the stock one on the left, BCM on the right.  Second picture shows it sitting in the bolt. 

I'll let you know how it goes! 

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[czfanatic_]

Hey guys,

I just got back from the range, and I am cautiously optimistic. So far, the gun is functioning better with the BCM enhanced extractor spring compared to the stock one. 

I was able to put 8 full mags through the gun with zero malfunctions of any kind. 

I think it is too early to call this a victory, as I want to get more rounds through it, but this is a promising start. 

Anyone wanna volunteer to help me test this out?  The extractor spring kits are less than $5, and it would be great to see if someone else could corroborate my findings. 

So far, so good.  I'll keep this thread updated as I put more rounds through the gun. 

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[wags68]

Wow, that is a great and promising start!  I will have to check into this if mine starts having issues.  I just replaced the hand guard on my 7.62x39 with a 922r kit hand guard and have not had a chance to shoot it.  I will be updating this thread as I get time.

[America_First]

Some really great ideas being thrown around here. 

Quick question, I noticed there are a considerable amount of people with this malfunction.  I'm just getting some ideas thrown around, the other day I had 4-5 in a string of 20-rounds once I started firing while standing (60 rounds fired from a rest with no problem before).  I'm thinking my thumb, with a typical (modern) thumb over bore grip was interfering with the charging handle locking and remaining unlocked, maybe causing the extractor to not get a reliable grip on the spent case as the BCG met resistance before it locked completely forward (extractor is longer on 7.62x39 models than 5.56x45). 

Once I changed my grip, testing the theory by resting the hand guard on my palm, then after with a clamp behind the charging handle; I fired 120-rounds without issue. 

[czfanatic_]

I just got in 500 rounds of Barnaul ammo and want to try that out, so I'm making a second trip to the range today.  Will end up putting another 200 through it.  I'll let you guys know how it goes.

Been using mostly Golden Tiger (2.5k rounds), and approx 80 rounds of Tulammo so far.

[Mercs]

I just got in 500 rounds of Barnaul ammo and want to try that out, so I'm making a second trip to the range today.  Will end up putting another 200 through it.  I'll let you guys know how it goes.

Been using mostly Golden Tiger (2.5k rounds), and approx 80 rounds of Tulammo so far.

My guns like the Barnaul just as much as Golden Tiger, and I find it to compare favorably in the accuracy department also


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[America_First]

I just got in 500 rounds of Barnaul ammo and want to try that out, so I'm making a second trip to the range today.  Will end up putting another 200 through it.  I'll let you guys know how it goes.

Been using mostly Golden Tiger (2.5k rounds), and approx 80 rounds of Tulammo so far.

Any update?