So I'm curious about the pressures at work in these blank cartridges...
or maybe I should say, where these are designed to operate. For whatever it is they do when they are discharged, a large part of the equation is whatever is resisting the blast. In the case of their actual design, it's going to be some sort of industrial nail or brad. In the case of these guys and their testing, it's a lead pellet of known weight.
When you take these little blank rounds and you put an obstruction in front of them that is -NOT- what they were designed to do, you are altering the max chamber pressure of their design... which I can't say we even know from the get-go. Off hand, I can't even guess if a 14 grain pellet is lighter or heavier than whatever the nail or brad is that's meant to be used in the industrial application for which they were intended.