Crimson trace makes a laser grip for the Ruger Mk. II & Mk. III.. I don't know if the Mk. IV used the same grip configuration. If so the it should work..

I would contact Crimson Trace at Phone: (800) 442 - 2406 M - F, 7:00 a.m. - 4:30 p.m. PST to see if they have gotten around to the Laser Grip for the Mark IV ---- google.com/search?q=Ruger+MK+IV+laser&tbm=isch&source=iu&ictx=1&fir=rKOYOoqBr_oQ4M%253A%252CzHqHdHUw_t3B4M%252C_&usg=AI4_-kQldhMy_KN6y5AZ7xxLoc4PCyJ4og&sa=X&ved=2ahUKEwjEy4vt75HgAhWzCTQIHeUADf4Q9QEwDHoECAMQBA#imgrc=rKOYOoqBr_oQ4M: