Yeah that's wide open, I can see right through them, plus I straightened a thick paper clip and pushed it right through ... I think its the very tiny holes on the shaft above the threads on the sides that help the air flow that look like they are jammed with white filler that's not helping, I tried to jam a needle in those but it doesn't seem to help they seem very resistant to even a needle
Now I realize that with a hole in the center they should draw perfectly fine because it should be wide open, but they don't, its gotta be the bottom design is different and is causing a airflow restriction from that bottom point as well because when off device it would be acceptable but on device even very loose it is not ... I am using a Provari btw ... ive had these many times before same exact model of these totally diff draw on same device
Something with that bottom flange or the small holes on the side or the way it seats is causing a major air flow restriction and making it very very tight, and they get worse as they get used
Update: So using the same tanks with a Boge versus Iken removed from device but filled and primed ... cover very botton center air intake hole so it has to intake air through the tiny side air holes on shaft is a major difference, so those tiny holes on side of shaft must be obscured in some way on the IKEN, taking a needle and trying to hollow them out doesn't work, perhaps if I get around to It I will try some tiny drill bits by hand or on my milling machine to just pierce those holes and widen them a little bit by just sinking them very slightly as they are, basically just cleaning them out some to see if its merely just there that's restricting and not something further up or down inside that's causing it.