HBI Gas Port Sizes?

[MeatAxe]

Finally got a set of pin gauges to accurately measure the size of the gas ports on my 11” 7.62x39 Bren 2Ms. Here’s what I came up with:

Position 1 —   1.89mm.    (0.0745”)

Position 2 —    2.46mm.   (0.097”)


Now, I have not had any FTE, etc. malfunctions, but back when I was actually shooting it (before I realized it was going to be so bleeped difficult to get parts) I did not note whether it was ejecting at 1, 2, or 3 o’ clock angles.

So, I’m wondering if it would be worth risking my (basically unobtanium) gas tube to a shipper to send it to HBI and back to drill the #3 position, since they may just duplicate the size port I already have.

Does anyone know what size HBI’s gas port is for the 11” x39 Bren 2?

Also, what size ports do other folks have, whether they’re Bren 2s are malfunctioning or not?

Thanks!

Also, FYI, I found a more or less reasonably priced set of plug pin gauges, which are probably the easiest and most accurate way to measure gas ports and other such orifices:

https://allindustrial.com/all-industrial-55102-190pc-m1-061-250-plug-pin-gage-set-minus-steel-0002-tolerance/

[shooter_from_show-me]

While I don't have any pin gages. Third setting is most definitely smaller.

I do understand your apprehension about sending and trusting a common parcel carrier to get your parts there. I was the same way with my 11" 556 gas regulator.

Ended up shipping it in a small flat rate USPS PRIORITY mail carton on a Thursday from KC area and was delivered that Saturday morning to their mailbox. I was shocked one day travel time to Tempe AZ.

Mike B said they'd most likely get it out the following Friday and they did. Even shipped FedEx 2nd day

I'd go on and send it to them   just got mine back today.

[MeatAxe]

While I don't have any pin gages. Third setting is most definitely smaller.

I do understand your apprehension about sending and trusting a common parcel carrier to get your parts there. I was the same way with my 11" 556 gas regulator.

Ended up shipping it in a small flat rate USPS PRIORITY mail carton on a Thursday from KC area and was delivered that Saturday morning to their mailbox. I was shocked one day travel time to Tempe AZ.

Mike B said they'd most likely get it out the following Friday and they did. Even shipped FedEx 2nd day

I'd go on and send it to them   just got mine back today.

The advantage for you is that 5.56 gas tubes are (occasionally) available at CZ USA and from other east bloc vendors. Not so with 7.62x39 gas tubes.

However, I hear now that CZ has finally come up with a fix for the x39 guns, a redesigned gas tube. They quietly announced this around April Fools’ Day. What few were available are gone now, but you can contact CZ USA and be put on another wait list.

[Sean1]

Hopefully in about 3 weeks, I'll have an adjustable gas regulator prototyped for testing. Stay tuned.

[MeatAxe]

Hopefully in about 3 weeks, I'll have an adjustable gas regulator prototyped for testing. Stay tuned.

Looking forward to it!!

When CZ drops the ball, it’s up to the customer base / aftermarket to find a solution.

[Sean1]

Does anyone know what kind of PSI is coming out of that port hole?

[MeatAxe]

Does anyone know what kind of PSI is coming out of that port hole?

I have no idea how you could even measure that. Probably takes some specialized engineering equipment.

Anyway, one little piece of info that might be helpful, if you weren’t already aware of it:

The FN SCAR gas system uses little screw-in jets of different sizes to adjust gas flow. Might be useful in dialing in the sweet spots for your prototype gas regulator:

https://www.parkermountainmachine.com/product/pmm-scar-1617-stainless-steel-gas-jets/

Also, as you probably know, the FN FAL uses an adjustable sleeve with 6 or 8 different sized gas ports over the gas plug / block to bleed off gas to varying degrees, which is probably the best gas adjustment system of any issued military rifle ever devised.

Good luck with your endeavor!!!

[Sean1]

Does anyone know what kind of PSI is coming out of that port hole?

I have no idea how you could even measure that. Probably takes some specialized engineering equipment.

Anyway, one little piece of info that might be helpful, if you weren’t already aware of it:

The FN SCAR gas system uses little screw-in jets of different sizes to adjust gas flow. Might be useful in dialing in the sweet spots for your prototype gas regulator:

https://www.parkermountainmachine.com/product/pmm-scar-1617-stainless-steel-gas-jets/

Also, as you probably know, the FN FAL uses an adjustable sleeve with 6 or 8 different sized gas ports over the gas plug / block to bleed off gas to varying degrees, which is probably the best gas adjustment system of any issued military rifle ever devised.

Good luck with your endeavor!!!

Thank you for the info. My prototype though yet to be tested is designed to have an on the fly dial in adjustment.

[MeatAxe]

Does anyone know what kind of PSI is coming out of that port hole?

I have no idea how you could even measure that. Probably takes some specialized engineering equipment.

Anyway, one little piece of info that might be helpful, if you weren’t already aware of it:

The FN SCAR gas system uses little screw-in jets of different sizes to adjust gas flow. Might be useful in dialing in the sweet spots for your prototype gas regulator:

https://www.parkermountainmachine.com/product/pmm-scar-1617-stainless-steel-gas-jets/

Also, as you probably know, the FN FAL uses an adjustable sleeve with 6 or 8 different sized gas ports over the gas plug / block to bleed off gas to varying degrees, which is probably the best gas adjustment system of any issued military rifle ever devised.

Good luck with your endeavor!!!

Thank you for the info. My prototype though yet to be tested is designed to have an on the fly dial in adjustment.

A lot of Bren 2 owners would be interested in what you come up with, especially since CZ itself has dragged its feet coming up with a solution. A multi-adjustable gas system would have avoided the problems we see with the x39 guns.

[Sean1]

A lot of Bren 2 owners would be interested in what you come up with, especially since CZ itself has dragged its feet coming up with a solution. A multi-adjustable gas system would have avoided the problems we see with the x39 guns.

I hope it will work out as intended. Will be testing it quite a bit.