Gas Port Size

[hitman49]

I am machining a 300 Whisper barrel and need to know what size the gas port hole needs to be. It will be a pistol position gas system and I will be shooting sub-sonic loads. Thanks for any help in advance.

[320pf]

I have barrel with the gas port in the pistol position that work with a port diameter between 0.075 to 0.083 inches. All of the upper that I have built all run both sub-sonic and super sonic loads without an adjustable gas block. I usually start with the port diameter at 0.073 and open it up as needed.


320pf

[hitman49]

Thanks for the info. Guess I will start with .073 and work my way up.