Egw contacted me here's what they said concerning their mounts for RDS on a 3rd gen.
Hi ,
Thank you for contacting us. We have found that S&W's typically do not have a true Novak cut, but one that is very close. We have mounts for S&W fixed rear sights that should work on your gun.
Viper/Venom S&W 1911 Fixed Sight Mount (fits Burris FastFire and Docter)