BRT CustomTune Gas Port

BRT CustomTune Gas Port™




The BRT CustomTune Gas port reduces gas system flow and can correct for barrels with large gas ports that exhibit excessive gas drive.

The port is installed inside the gas block or FSB between the barrel and gas tube.

After installation, it requires no user adjustments or maintenance.

It cannot fall out, come loose or go out of adjustement.

The gas port is available with a variety of port sizes to meet many applications.



Installation requires removal and re-installation of the low profile gas block or front sight base.

Installation is relatively easy and may take less than an hour, start to finish.

Includes FREE SHIPPING.  Please allow 3-5 days for items to ship


Suggested Sizes:

5.56 11.5" CAR: .070"

5.56 16" CAR: .063"

5.56 16" MID: .076"

Please email for recommended sizes for specific applications.


Here are a few examples.  This 11.5" barrel had a large gas port.

It was very overgassed, cycled too quickly and ejected brass forward.

A CustomTune Gas Port was used to bring it back down to normal.

Function is now exactly where it should be and it shoots great.



The owner then wanted to run this same upper with the suppressor.

Suppressors add even more gas drive, so the gas port was swapped out with a smaller one.

With the smaller port to compensate for the suppressor, it functions just like before.


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