can this be used with a 3x magnifier — 2 Answers

It will work with a caveat... the cantilever mount is not the correct height to work with the HM3X or any other absolute witness height magnifiers. The HS506 has a 1.56” mounting height and does not line up with the magnifier by 0.11 inch more or less. This was also confirmed by Holosun customer service and they told me that I will need to replace the cantilever mount with one that is made for absolute or lower 1/3 co-witness. In my case I used a Vortex CM-305 mounted in reverse cantilever orientation to get the right height for absolute co-witness and to clear the battery compartment. I believe Vortex sells both heights so you should be able to make it work for either height you want but you will still have to replace the cantilever mount.