I have had no zero problems at all. My EP-5 is mounted with 34 mm picatinny rings extra high on a Ruger RPR rifle to clear the handguard. I was able to zero the bullet impact with in just a few clicks of rt to lt mechanical zero. Look on the internet about how to check your optical zero then check your mechanical zero. I found the EP-5 to be very close in rt to lt and up down optical vs mechanical. The Ruger RPR has a 20 minute rail so final zero leaves enough elevation to get to 260 yards with standard SK ammo.