So I have a custom 18” barrel that is a mid-length gas with a port of 0.094. It’s hella overgassed. The person who made it was pretty new at the time. Shoots well though.

I already plan on running a BRT EZ-Tune so that’s not as much of a discussion as just generally what do you think a gas port size should be on an 18” mid-length? Also planning to run a flow-through style suppressor (I’m a lefty) and mil-spec spring and carbine buffer to make it as soft shooting as I can.

Example: most 13.9-16” mid-length gas ports are 0.074-0.078. So with the 18” having more dwell time, you’d want a smaller port. Would a 0.068 or 0.070 or something be better for the 18” mid-length? Just curious on people’s thoughts. Haven't found a good resource so if you know of one let me know.

18” mid length shouldn’t exist.

https://docs.google.com/spreadsheets/d/1tXunBDX5Gaz87BqxwNxDUlWNK9nEv-cZEQoLq2JXXrk/htmlview#gid=766121382

https://sites.google.com/view/black-rifle-haven/gas-port-reference-charts

Thanks

I called Sionics, and they would not give their port sizes for any barrel option.  

Thanks for the post.

Had an 18" rifle gassed barrel and had to open up the port to get it to run.  Would have been perfect size for mid-gas.  Go figger....

A case can be made for intermediate for 18”.

My 17” rifle with .093 port runs with 5.56 when above freezing. Crane spec was .104 IIRC.

Next project is a 16.5 rifle with .089 port. I won’t run it without a can.