3,251 Posts. #7 · Jun 30, 2014 (Edited) I could be wrong on this, but years ago at a class I was told that the Glock adjustable rear sight was meant to be adjustable over the range of Glock non-adjustable sights available. That would mean 6.1 mm, 6.5 mm, 6.9 mm, and 7.3 mm. Hope that helps. Dave.