Once you turn the pin to the left as far as it will go, that's as low as it will get. There are some attys that still won't sit completely flush. Some attys have 510 connectors that are a little bit long, and will bottom out before they are flush. I'm sure that when Rob designed the new style 510 adjustable connectors, he had to choose a happy medium, as far as depth. I don't have an RM2, so I don't know. But I do have a couple RM4s, and they too have slightly longer 510s, and do not sit flush. I generally use an o ring under the atty, to take up the space. The o ring also has the added benefit of taking the stress off the 510 connections, in the event of a drop.