Author Topic: Parts falling off!  (Read 3472 times)

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Offline WNC Seabee

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Parts falling off!
« on: May 07, 2023, 07:06:30 PM »
I have a new-to-me 14" Bren 2 w/an HBI handguard.

Took it out today for the first time and ran ~100 rounds or so through it. Terrible accuracy, 55gr, 69gr and 75 grain match all had less than acceptable accuracy. Shot from a bench with bipod and 8x optic.

Anyway, got pretty frustrated and picked this thing up to put back in the truck.  That's when I heard a rattling around and had this guy fall out of the handguard...seems to be part # 106 from the diagram. I didn't find any screws on the ground, but they could have just been lost in the brass and gravel.

My question....when the HBI handguard is added, does this part stick around or is it superfluous? Do I need to reinstall?

I imagine a loose part rattling around in contact with the barrel may have contributed to my accuracy issues.

Edit: how do I add a pic?! Working on that…

« Last Edit: May 07, 2023, 07:14:57 PM by WNC Seabee »

Offline MeatAxe

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Re: Parts falling off!
« Reply #1 on: May 07, 2023, 08:07:14 PM »
^ Well, that’s the barrel sleeve, which is pretty integral to holding the barrel, receiver and hand guard together.
 
If you feel competent enough, I would take front end and barrel all apart and off the receiver and examine for damage from firing it in that condition. If not, send it into CZ USA service, such as it is.

Can you post a pic of the outside of the junction between the receiver and hand guard?

« Last Edit: May 07, 2023, 08:18:56 PM by MeatAxe »

Offline WNC Seabee

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Re: Parts falling off!
« Reply #2 on: May 07, 2023, 09:17:48 PM »
Thanks!

Offline MeatAxe

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Re: Parts falling off!
« Reply #3 on: May 08, 2023, 08:37:52 AM »
Actually, scratch what I said earlier. If you have the hbi hand guard, that doesn’t use the barrel sleeve. Whoever sold you your Bren just stuck that piece in there for whatever reason. The barrel sleeve(s) are integral to the stock Bren 2MS, which has @14 torqued screws in its “hand guard” configuration, but that’s another can of worms…

I think your issue is probably the torque on your 4 remaining mounting screws on the hbi hand guard. The two barrel sleeves, which are integral to the stock “hand guard” come off with the lower rail removal. Problem is, I don’t think hbi has a set torque value for those 4 remaining screws that hold it all together. Initially they advised 90 in.lbs. (as opposed to 64 in.lbs. as advised by CZ in its stock configuration) but then people literally started getting their extruded receivers pinched, which actually interferes with the action. I’ve seen various “interweb recommendations” of anywhere from 20 to 40 to 90 in.lbs., which is crazy.

I had chamber blowback when I used the hbi hand-guard (thick black streaks of powder on spent cases), which I attributed to some headspace interference. So I went back to the original 14 screw MS configuration, much as I hate it ergonomically. But at least it functions properly.

Of course, the Bren 2 to have is the original “military” S model which had no hand guard contrivance at all - just an extended receiver with M Lok slots. Of course, those few S models are long gone, no longer available in the US market, for whatever stupid reason CZ came up with.

Anyway, I think the torque on your 4 remaining barrel / receiver / hand guard screws is likely your accuracy issue…good luck!!!
« Last Edit: May 08, 2023, 08:48:12 AM by MeatAxe »

Offline WNC Seabee

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Re: Parts falling off!
« Reply #4 on: May 08, 2023, 08:55:45 AM »
I spent a bunch of time last night trying to figure out how that piece was going to go back on! Figured I had other parts get gone. So thanks for popping back in with the clarification.

I'll try torquing those screws evenly and playing with the values until it finds a happy spot.

Offline MeatAxe

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Re: Parts falling off!
« Reply #5 on: May 08, 2023, 09:35:00 AM »
I spent a bunch of time last night trying to figure out how that piece was going to go back on! Figured I had other parts get gone. So thanks for popping back in with the clarification.

I'll try torquing those screws evenly and playing with the values until it finds a happy spot.

HBI has a video installation tutorial on their website, such as it is. You might want to get some new screws and “Nord Lock” torque washers (available at Fastenal) when you re-assemble.
« Last Edit: May 10, 2023, 09:25:56 PM by MeatAxe »

Offline WNC Seabee

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Re: Parts falling off!
« Reply #6 on: May 15, 2023, 11:48:16 AM »
Torqued the hand guard/barrel screws to 30in/lb with weird results.

Put a direct thread can (SiCo Omega) on the end and got acceptable results, 1.7MOA and ringing man sized steel at 500yds easily.

Took the can OFF and replaced the factory flash hider...opened up to 4+ MOA. All factory ammo in 55, 69 and 75gr.

What's up with that? I'm loving how this gun handles in general, but the accuracy is gonna kill it for me!

Offline MeatAxe

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Re: Parts falling off!
« Reply #7 on: May 15, 2023, 06:54:28 PM »
Torqued the hand guard/barrel screws to 30in/lb with weird results.

Put a direct thread can (SiCo Omega) on the end and got acceptable results, 1.7MOA and ringing man sized steel at 500yds easily.

Took the can OFF and replaced the factory flash hider...opened up to 4+ MOA. All factory ammo in 55, 69 and 75gr.

What's up with that? I'm loving how this gun handles in general, but the accuracy is gonna kill it for me!


The Bren 2 has never been known for pinpoint accuracy. It’s more suited as a house, truck or backpack gun. At best, I’m getting @ 2” moa out of my 11” 7.62x39 with Hornady SST. But that’s using the 14 screw OEM “hand guard” as engineered by CZ.

You might try torquing up the 4 barrel screws incrementally and see what you get. 64 in.lbs. is what CZ recommends with the factory for-end set ups. I would be wary of going any higher than that lest you pinch the receiver (as some have done using HBi’s initial recommended torque of 90 in.lbs.).

Unfortunately, from what I can see, there seems to be a wide performance variation between individual Bren 2Ms’s when fitted with HBi hand guards.
« Last Edit: May 20, 2023, 01:21:19 PM by MeatAxe »

Offline WNC Seabee

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Re: Parts falling off!
« Reply #8 on: May 15, 2023, 09:46:28 PM »
Will do on the incremental torque.

I appreciate it!

I "saved" several hundred $$ on this gun because the OEM handguard and related bits were MIA. I'm beginning to wish I'd just bought one NIB!

Offline MeatAxe

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Re: Parts falling off!
« Reply #9 on: May 20, 2023, 01:10:48 PM »
Will do on the incremental torque.

I appreciate it!

I "saved" several hundred $$ on this gun because the OEM handguard and related bits were MIA. I'm beginning to wish I'd just bought one NIB!


Hopefully, you’ll find the accuracy sweet spot as you increase your torque. Otherwise, I’m sure somebody would sell you their OEM take off parts. Unfortunately, these HBI hand guards seem to be hit or miss.

It’s just a shame that CZ decided to fit the 2Ms with this totally useless  “hand guard” contrivance for the US market. Not only is it totally unnecessary, but it forces owners to make up another 922(r) part if you convert to a rifle, which may be a thing depending on the outcome of the pistol brace ruling.

Good luck!!
« Last Edit: May 20, 2023, 01:25:27 PM by MeatAxe »

Offline WNC Seabee

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Re: Parts falling off!
« Reply #10 on: May 22, 2023, 09:08:43 AM »
I torqued to 30 in/lbs, then 35 in/lbs and added some loctite. That seems to have done the trick. I won't be convinced until I have another range trip or 2 AND several runs through a stage with dump barrels and other ways of knocking it around.

Offline MeatAxe

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Re: Parts falling off!
« Reply #11 on: May 22, 2023, 05:43:06 PM »
I torqued to 30 in/lbs, then 35 in/lbs and added some loctite. That seems to have done the trick. I won't be convinced until I have another range trip or 2 AND several runs through a stage with dump barrels and other ways of knocking it around.

Awesome! I hope it holds up. I’ll try that method if I have to put the hand guard back on for 922(r) compliance.

Offline mig1nc

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Re: Parts falling off!
« Reply #12 on: July 16, 2023, 10:13:33 AM »
The monolithic uppers are putting in work in Ukraine and in Russia with the various Russian rebel factions.

I wish they would bring back the monolithic upper to the American market.


Sent from my iPhone using Tapatalk Pro

Offline armoredman

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Re: Parts falling off!
« Reply #13 on: July 16, 2023, 06:19:27 PM »
Any updates? How is it working now?

Offline WNC Seabee

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Re: Parts falling off!
« Reply #14 on: July 16, 2023, 06:24:21 PM »
Doing great! I ran it in a Run n Gun match yesterday and did well enough. 14.1” barrel that seems to like 55s better than the heavy stuff, but I was getting my hits out to 550yds

No issues with torque, etc since I dialed it in.