I have the Z5 3.5-18 BT on my 300 WM. Glass is great. I have the first setting at 200, with the others at 300,400, and 500. They work pretty well and it is repeatable. The negative I found is that with these settings, the adjustment will only reach 600 yards before bottoming out.
I have ordered a 20moa base to remount the scope and gain added adjustment. It should give me all I need for this rifle. I don't intend to shoot extreme distances with it.