MOA info on dot sights

My underestaning is that all MOA info is based on a distance of 100 yards. Example: a 4 moa dot covers approx. 4 inches at 100 yards. that would mean that 4 MOA covers 8 inches at 50 yards and 10 inches at 25 yards. Am I correct on these assumptions? thusly it is better to get the smallest MOA you can find for the right price.

Sorry, your wrong. The dot would cover 2" at 50 yds.

OM65 is correct. The closer the target the smaller area it covers.

1" at 25 yds
2"at 50 yds
4" at 100 yds
6"at 150 yds
8" at 200 yds
and so on                          


Virgil

+1 on the 2 above explanations

MOA is Minute Of Angle which is 1/60 of 1 degree. At the optic is where the angle starts and it spreads out the farther away the target is.

Click adjustments
If your optic has 1 MOA click adjustments. 1 click at 50 yards should move the POI 1/2"
1/4" at 25 yards.

- Dave

Well the others are almost correct but not exactly. moa is minute of angle. Meaning 1/60th of a Degree. Calculating it using the Tangent of 4 minutes multiplied by the distance 100 yards the circle will be 4.188" in diameter at 100 yards. 8.376" at 200 yards and 2.094 at 50 yards and so on.
 Not much to worry about in pistol but if you were shooting at the moon you would miss it by quite a bit!

Frank

I guess I didn't realize I could be off .188". I will have to compensate. I have several ways to do that. This is a red dot were talking about. Changing the intensity of the dot I can get something that looks like a small dot, or I can crank it up and get a bright red ball that has what looks like solar flares coming out of it. Either way I am positive that it won't look round to me anyhow. All joking aside. I have noticed a large difference in the size of the dot in the same model's of ultradots. I think the 4 MOA is a pretty rough estimate and it depends on time of the day/week/month the unit was made. If you have multiple Ultradots you have probably noticed the same thing. Or dots of another manufacture may be bigger when it is supposed to be smaller or vice versa. I think it is more of a guesstimate, so 4" at 100 is close enough for now.

I find putting a small aperture on the shooting glasses like the Merit helps keeping the dot uniform and round.
 Your right it does change from scope to scope! I don't undersade why it can't be made like a c=scope with cross hairs, they don't move and are always in the center.
 I added the information to describe what moa is. Used in shooting because one point is fixed such as iron sights. The front sight is usually fixed and the rear adjustable so the theoretical sight movement becomes a Trig function due to the triangle created and calculated buy using the Tangent of an angle. Usually 1 minute is consider to be 1" at 100 yards.