I guarantee that there is no air flow apart from where the set screws are. (I know the flow from the LL comes from below, but on the EO it's pushed so far in you can't see those holes at all ... I can't get a fingernail in the gap.) When I put my fingers over all 4 holes and form a vacuum with my mouth over the top of the hole and inhale there is no flow (before I loaded). If I take 1 or more finger off the set screw holes then I get "some" air flow (extremely restricted as I indicated initially).
Perhaps that's happening in your core when it's
cold (because it's
already plugged at the vents.....) but it's not how it works when it's being run.
I have two cores here, one a little fuller than the other. One behaves like you suggest,
the other does not (it draws much freer since it's got no excess at the vents). I just put the 'slow' one it the Cera, warmed it up a bit and 'popped it clear' and found
I could then block the four holes and draw normally (until it cooled enough to plug again). At the risk of your fingers getting burned, I suggest you try that test (test it in the state it's used in).
And you can definitely see at least part of the holes when the core is new (or very clean) and you look close enough. Early on in testing Tim and I discussed this very point. I wanted to open it up to test for easier production only to be advised that had already been investigated and optimized. The partial covering of the vents is precise and intentional.
Let me ask a rhetorical question that might set this straight? If it's not there to provide and control air input why did TV go to the expense of putting the bevel in the body? It would have been cheaper and far more sure to seal to not put in.
OF