I was curious the same when we put the HD together and wanted to see how consistent the rack travel was... I held about a 16" piece of a spruce 2x4 stud on edge and engaged the rack and it slightly indented the wedge side of the 2x about an 1/8" thick, if that. It made the same indention half a dozen times so mine gets within an 1 3/8" or so consistently.
I thought 2 x 4 was a great way to test the wedge distance. So since you guys like pictures. Here is a short video. I do think my wedge is set to far back. Might have to give super split a call. But I know from a conversation with the Split Second engineers this is not a simple weld.