Originally Posted by BigB
Question? Am I to assume that a RDS with a 5 moa would group within 5" @ 100 yds?
No. First, the optics have nothing at all to do with the accuracy of the rifle, they only help you achieve the accuracy of the rifle by making it so you can see where you need to put your round.
A 5 MOA RDS means that the dot in the reticle covers a 5 inch (approximate) circle on a target 100 yards away. It has no effect on where the rounds will hit from any given rifle. If your rifle is capable of exactly 5 MOA, then all rounds should land within the dot. If your rifle is only capable of 10 MOA, then statistically, only half of your rounds should land within the dot. If it's a 1 MOA rifle, then you should theoretically get a nice 1" group where the center of the dot lies, IF it's sighted in properly. But it's harder to get a one inch group if your target is covered by a 5" reticle.
A 5MOA RDS on a 1 MOA rifle is a severe hindrance to the achievable accuracy of the rifle.