2.8W Laser setup not possible within specs?

Has anyone here set up the 2.8W laser on their M2? I went to install mine and it tells me to mount it in the sled, and then lower the Z axis until it is 1/8" from the material. I have the Z down as far as it can mechanically go, and the laser in the mount as far as it will go, and I am still over 1/2" off from the 1/8" focus point. Is there something I am missing from the instructions? Any help would be most appreciated. Thanks.