Author Topic: Suppressed gas key hole size on the Bren 1 & 2  (Read 275 times)

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Offline Mr_5lade

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Suppressed gas key hole size on the Bren 1 & 2
« on: January 14, 2020, 10:43:16 PM »
Hey all, I’m going to rework the gas key on the 11” 805 to have a suppressed setting and also going to drill out the “off” setting on the 8” Bren 2 5.56. Is there a consensus of drill bit size? It looks as though the “regular” setting hole size for the 805 is 1.2mm - is this correct? I’m not sure on the 2... Any input would be appreciated. Thanks  8)

Offline Aries144

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Re: Suppressed gas key hole size on the Bren 1 & 2
« Reply #1 on: January 15, 2020, 05:56:33 AM »
Pretty sure you're the first and this is going to be a trial and error thing. Start small, test, open it up a little, test, etc. If you can't shoot nearby to your drilling tools, you might try precision drilling a starter hole smaller than you think is needed, then using a hand tool at the range to open up the hole until desired function is achieved.

If you can lay hands on a high speed camera (there are some cheap enough to use for diagnostics like this), you can compare the bolt velocity when the rifle is unsuppressed/normal gas setting to your suppressed/suppressor gas setting and stop enlarging the hole when comparable timing is achieved.

Offline beanz2

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Re: Suppressed gas key hole size on the Bren 1 & 2
« Reply #2 on: January 15, 2020, 10:54:07 AM »
I’m not of any authority, but I recall a guy on arf.com saying his aim is 0.8 mm for the suppresses setting.

His concern is surface treatment of the metal after he drills it as the drill leaves unprotected metal behind.

Hope someone can shed a light here...


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Offline Aries144

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Re: Suppressed gas key hole size on the Bren 1 & 2
« Reply #3 on: January 15, 2020, 07:50:37 PM »
If you can find a company that nitrides steel parts, ask them what they think about re nitriding an already nitrided part after drilling.

The gas port on the Bren 2 barrels is drilled pretty close to the chamber compared to other designs, which means higher pressures and temperatures from those gases. Retreating the part after drilling wouldn't be a bad idea to reduce erosion, if re nitriding is possible.

Offline Mr_5lade

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Re: Suppressed gas key hole size on the Bren 1 & 2
« Reply #4 on: January 15, 2020, 10:05:43 PM »
Great info you guys I appreciate it. I do have an AK shop here that I believe nitrates. I will do a write up once I’m done with this project 👍 The suppressor is going to be a Dead Air Wolverine. I may also try the Silenserco Omega 300 on the gen one to compare back pressure.

Offline Aries144

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Re: Suppressed gas key hole size on the Bren 1 & 2
« Reply #5 on: January 17, 2020, 06:49:11 PM »
Don't forget to post back when you get it done! I'm particularly interested in what the nitride shop says about re nitriding.