Hello toku58, I do not doubt the 250bar bottles that FX have been using are tested to well above 300bar, however this is not the narrative, "NEW 300bar" bottles is what FX are hailing, I am trying to ascertain if they will be releasing a 580cc 300bar with their new M3 valve included, or is it only the "300bar, 480cc" they are going to put out.
Where that the case, the question is , why go with 300bar/480cc when 240bar 580cc would hold AROUND the same useable air, without the risks of 300bar.
good luck.