A hard question to answer for a few legitimate reasons. For some reason over the years, Rockies dont always seem to be have been assembled in a "uniform" way. It could be as simple as that whoever does the assembling of the grind adjust scale sticker to the hopper, from time to time, doesnt always put it in exactly the same position. Therefore, the numbers on the scale of one grinder when compared to another grinder may not necessarily reference an "equivalent" grind. Additionally, the appropriate grind setting for any particular individual coffee, in any particular individual grinder, for any particular individual espresso machine, will differ. Not just because the equiment will differ in things such as pump presure and flow, but also because of the differing density / oil content of any particular coffee. And of course the humidity on any particular day will affect the density of the coffee as well...possibly needing a different grind setting at any particular time. This is why baristas (cafe or home) need to know enough to be able to "dial in" their coffee beans and equipment together for best effect, at any particular time including as the beans age and stale (losing density), as well as when a new supply of the same blend is purchased OR a different blend is purchased (meaning the beans will differ in density to the last lot, needing to be dialed in again...). Additionally some baristas like to does 'up', and some like to dose "down". This requires grind settings to be set according to the dose the barista likes to use, finer or more coarse....to get the kind of resulting pour that the individual barista likes... Ergo, the "right" grind setting for you today, is whatever it is, and tomorrow it may differ slightly...or not, and may be different to someone else using the same equipment and beans, or same equipment and different beans. You need to dial in using your technique and beans, to get the best coffee for you, and whatever number that turns out to be, is what it is. Hope that helps.
