I have a rifle sighted in at 100yds.

 

I want to adjust for 300 yds. I know the bullet will drop 15.7" at 300yds (it will hit the target 15.7" below the bullseye if I don't adjust).

 

My scope has 1/4 MOA adjustments, and 1 MOA will move the bullet approximately 1" at 100yds.

 

Will 1 MOA move the bullet 3" at 300yds?

 

If that's try, I need to move the scope up (15.7" / 3" per MOA) = 5.2MOA, or 21 clicks up.

 

Am I right?

Aha.

 

A circle of 300yds radius has a circumference of (300yds * 2 * 3.14 * 36"/yd) = 67824".

 

There are 21600 minutes in a circle (360 degrees * 60 minutes/degree).

 

So, at 300yds, one MOA is 67824/21600 = 3.14".

 

So, each MOA is 3.14" at 300yds.

 

If I want to move it 15.7", thats 5.0 MOA, or 20 clicks!

Yep, you have it. 1 MOA at 100 is 1", 200 = 2", etc. 4 clicks per MOA at 100.

How did you calculate the 15.7" drop at 300 yards?

Probably a ballistics calculator or chart.

Probably a ballistics calculator or chart.

I have two ballistics programs on my iPhone I use all the time, but in this case, Federal Gold Match competition ammo has his info in a chart onhe box (along with other data, plus I matche e calculator).

Yep, you have it. 1 MOA at 100 is 1", 200 = 2", etc. 4 clicks per MOA at 100.

 

Trying to fully understand this. But I'm confused by 4 clicks per MOA at 100. Isn't 4 clicks per MOA independent of distance?

Trying to fully understand this. But I'm confused by 4 clicks per MOA at 100. Isn't 4 clicks per MOA independent of distance?

 

Yes, the four clicks per MOA is fixed; it's the way adjustments on the scope work.

 

MOA is a minute of angle. As you get to a larger and larger distance/radius, the size of the MOA goes up.

 

At 100yds, an MOA = 1.05".

 

At 200yds, an MOA = 2.09".

 

At 300yds, an MOA = 3.14"

 

At 1000yds, an MOA = 10.5".

 

Each click on my scope is 1/4 MOA, so at 100yds each click would move the point of aim 0.26", but at 1000yds each click would move the point of aim 2.6".

 

-Dave

Just remember the scope matters. Unfortunatly in the imperial world there are variations on the click value of arc a scope subtends. This is why I prefer mill based scopes. You need to know if your scope is adjusting in IPHY, SMOA, moa etc etc. At close range the error isnt that much but the further out you get it becomes compounded. For example, say your scope is adjusting in IPHY (inch per hundred yards) and you calculating in true moa, 1.047. Well, at 1000 yards for a 308 that could be a 20" deviation at the target end!