In general, each combination of barrel length and gas system needs it’s own gas port size to scale down the different amount of available gas drive provided by that combination.
For a given barrel length, a longer gas system needs a larger port.
For a given gas system, a shorter barrel needs a larger gas port.
Yeh all in all BCM has that configuration down to a tee.
I now have three 14.5 Middies, and they digest everything I feed them…
I shot another 250 rounds or so of American eagle 223 and hornady 223 urban tap 55GR yesterday, without any issue. I’ve also “limped” the gun by not shouldering it and just letting the gun’s own weight move freely during recoil, and everything still functioned just fine. I am now more confident in this rifle.