My new RDO should be delivered by Christmas. It will be installed on my new Aero Precision AR15 with 18-inch SS fluted bbl and rifle length gas system. The primary purpose of this AR15 is home defense. I wanted to keep the gun light and the 4oz RDO will also provide a quick sight acquisition. I have run several calculations using a 55gr bullet at 3100fps muzzle velocity with JMB trajectory chart. I believe that the red dot sight should be sight-in at 50yds. The bullet would only be 1 inch low at 25yds, 1 inch high at 75 yds and 2 inches high at 100yds. The second zero would be at about 250yards. I would like to hear opinions from anyone who has a similar AR15 with a red dot sight primarily used for " social adjustment"