Bren reliability issues

[EE805]

Recently I've had some reliability issues with my Bren:

As of late I've had a few failures to go into battery; sometimes pulling the bolt back half way and letting it to will chamber the round, other times I have to drop the mag and clear it.

In addition, I experienced several double feeds when the Bren was hot after shooting a few hundred rounds.

After browsing the forum I came across a gas tube image that showed excessive wear on the normal gas setting port, and noticed that mine showed the same seemingly excessive wear.

Has anyone has similar issues? Is this something that's common?

Background:
I bought the Bren (16.2" FDE rifle) back in February 2019
I've shot primarily wolf gold .223 through it
I've used a variety of magazines, but mostly GI mags, lancers, and gen 2 pmags
I clean the bren after every range outing using Hoppes #9 products

[Type5]

Just curious, which Bren?

[Aries144]

It'd have to be a Bren 805, since there aren't any 16" bbl Bren 2Ss or Bren 2 MSs  in the US.

EE805,

Those failures to go into battery, they don't involve a cartridge halfway up the feedramp, but with the bolt on top of the cartridge case instead of behind it, do they?

Does the rifle malfunction the same way with softer shooting ammo, like Wolf 55gr?

Is your rifle still under warranty? If so, think about the above and include the answers in your email to CZ Customer Support along with a picture of the gas port.

If your rifle isn't under warranty, my first guess would be gas port erosion. Here's the replacement part: http://shop.cz-usa.com/ProductDetail/370002306562_Gas-Tube-805-162barrel-Length-Dual

[armoredman]

Was it hot handloads, or factory ammo?

[EE805]

Just curious, which Bren?

I should have specified in my previous post; it's a Bren 805.

[EE805]

Was it hot handloads, or factory ammo?

I haven't shot any hand loads through it yet, only the following ammo:

Wolf Gold .223 (55 gr)
Fiocchi .223 (55 gr)
M193 5.56 (55 gr)

[EE805]

It'd have to be a Bren 805, since there aren't any 16" bbl Bren 2Ss or Bren 2 MSs  in the US.

EE805,

Those failures to go into battery, they don't involve a cartridge halfway up the feedramp, but with the bolt on top of the cartridge case instead of behind it, do they?

Does the rifle malfunction the same way with softer shooting ammo, like Wolf 55gr?

Is your rifle still under warranty? If so, think about the above and include the answers in your email to CZ Customer Support along with a picture of the gas port.

If your rifle isn't under warranty, my first guess would be gas port erosion. Here's the replacement part: http://shop.cz-usa.com/ProductDetail/370002306562_Gas-Tube-805-162barrel-Length-Dual

Aries144,

Some of those failures have been exactly as you described; I see them exclusively when the rifle gets hot and it is being fired rapidly.

The other failure however - not going into battery with the bolt behind the round (maybe 80% in the chamber) - I see more frequently. I think this issue has occurred at least once with every type of ammo I've used (see previous reply). Could it be a magazine problem?

Yes my rifle is under warranty still; I took a picture and sent it to CZ support for comment.

EE805

[armoredman]

What setting is the gas port on?  Sounds like CZ-USA should probably take care of this for you, and it's time for a call tag for warranty repair.

[Aries144]

The first type of failure is a bolt-over-base malfunction, which I've most often seen when bolt velocity was too high. However, without seeing it myself, it could also be caused by a short stroke, which would indicate that bolt velocity is too low, lol.

The second failure you're describing makes it sound like the issue might be short stroking, perhaps due to gas leaking from in between the barrel's gas port and cylinder instead of driving the piston.

My best guess is that the issue is related to a worn gas cylinder. My amateur, non gunsmith recommendation is to get CZ to take it back for warranty work. Failing that, the first thing I'd try is replacing the gas cylinder and continue to diagnose from there if necessary.

[Aries144]

Also, have you tried running the rifle on the adverse gas setting? If that works, that helps narrow the problem down to the gas cylinder.

[EE805]

What setting is the gas port on?  Sounds like CZ-USA should probably take care of this for you, and it's time for a call tag for warranty repair.

The gas port was set to the normal setting; I have an email out to CZ USA and am awaiting their comment on a picture I sent of my gas tube. I also asked about the "8" marking on the gas tube. Any idea what the "8" stands for?

[EE805]

The first type of failure is a bolt-over-base malfunction, which I've most often seen when bolt velocity was too high. However, without seeing it myself, it could also be caused by a short stroke, which would indicate that bolt velocity is too low, lol.

The second failure you're describing makes it sound like the issue might be short stroking, perhaps due to gas leaking from in between the barrel's gas port and cylinder instead of driving the piston.

My best guess is that the issue is related to a worn gas cylinder. My amateur, non gunsmith recommendation is to get CZ to take it back for warranty work. Failing that, the first thing I'd try is replacing the gas cylinder and continue to diagnose from there if necessary.

Thanks for the info. When you say gas cylinder, are you referring to the adjustable tube with normal and adverse gas settings or so a different part of the gas system? Regardless of what part may or may not have an issue, it's disappointing that I'm having issues with my rifle after such a low round count (~2000 rounds).

In response to your other post, I have set the gas setting to adverse before, but the recoil was so violent (rifle was clean) that there were some cases of a failure where a spent case rotated 180 degrees and stayed in the action.

The rifle seems to malfunction when being fired rapidly/when hot; does that indicate anything further in terms of potential issues?

[EE805]

The first type of failure is a bolt-over-base malfunction, which I've most often seen when bolt velocity was too high. However, without seeing it myself, it could also be caused by a short stroke, which would indicate that bolt velocity is too low, lol.

The second failure you're describing makes it sound like the issue might be short stroking, perhaps due to gas leaking from in between the barrel's gas port and cylinder instead of driving the piston.

My best guess is that the issue is related to a worn gas cylinder. My amateur, non gunsmith recommendation is to get CZ to take it back for warranty work. Failing that, the first thing I'd try is replacing the gas cylinder and continue to diagnose from there if necessary.

I just watched some footage of me shooting my Bren and noticed that the ejection pattern was between 1 and 2 o'clock consistently which tells me that the rifle is in fact over gassed.

[the war wagon]

What setting is the gas port on?  Sounds like CZ-USA should probably take care of this for you, and it's time for a call tag for warranty repair.

The gas port was set to the normal setting; I have an email out to CZ USA and am awaiting their comment on a picture I sent of my gas tube. I also asked about the "8" marking on the gas tube. Any idea what the "8" stands for?

If you mean on the gas port key, that's a "B," not an '8.'  "A" is the normal setting; "B" is for "BOLLOCKS!!!  I've got dirt/mud/water in my gun, and I need to switch over to the "B" setting, so it'll actually run in this crappy condition!!!"... or something like that.   

Just switch BACK to "A" after you've cleaned it!