I have a BPS drum I built probably 7 years ago. I have never been super happy with the slide vent. I feel like as you close that vent down (not completely shut) you aren't really fully stoping each hole from drawing air.
It works ok but I think there is probably a better solution.
I haven't used it in a long time but if I'm running 275 I probably have less than one hole open on each vent.
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