If it fits like the IWC mount it will contact the front lip of the ACR hand guard and push the beam left slightly - you can put washers between the mount and the hand guard to fix the clearance issue.Also picked up right and left Magpul MOE Scout mounts today.
I read that they weren't compatible with the ACR due to vent spacing. But there isn't much difference in the ACR and MOE handguards.
They were cheap so I went ahead and bought them.
Couldn't you just mount a magpul rail section on the vent holes and have the light closer for easier activation?