I’ve got a couple of the Magpul’s, but run them on my 22’s…so keep that in mind. Height is going to depend on you and the terrain you want to use it in. Lay down and rest the rifle on a few objects of varying height to find the right fit for you. Some of us are a little (we’ll just say deeper) (ok, rounder) than others and might need a little more height. I haven’t had a problem with 6-9 and I’m not tiny. If you’re going to be somewhere you need it a little higher…get the taller one.