we just had this issue arise on a damage hunt out of harlowton and the rule says that we can not use any divice that projects a beam of light or laser aiming site. if you call the head warden in helena he can tell you if you have legel divise. reticals that only lite the crosshair or dot are good but no aim points is what they told use.
We had the local warden write a letter for my work in reguards to illuminated ret. It states the sight may not project light from shooter toward target, as a simple rule of thumb place your hand in front of the device in low light. If u see light on your hand then its illegal if not then you are good to go.