Advanced Marksmanship Question about effects of mirage

[rg1911]

I was at the range Saturday trying to get scope settings for a new load. The mirage was some of the worst I've seen, and at 400 yards, two shots (I wasn't going for group) could have a vertical dispersion of several inches. This is from a rifle that is consistently sub-MOA at 400+ yards.

The scope was set on 20X.

The question then is: Can mirage have such a drastic effect? I don't have a lot of confidence in the scope settings I recorded past 250 yards.

Thank you,
Richard

 

[Bigwheels]

In a word. Yes. Mirage is bending of the light between you, & the target. This gives the impression that the target is moving, which it's not, therefor your point of aim moves off the actual position of the target. I tend to call it target displacement.
I have seen mirage cause a target to move more than 2 moa back, & forth with the breeze, in direct sun. Set your rifle up, & bag it in on target in the early morning, & watch what the target does when the mirage starts running. You may be surprised.

 

[rg1911]

Thank you for that information. I remember reading about target displacement; I just did not realize that it could be so pronounced.

It sounds as though another trip to the range early in the day will be necessary to double-check the settings I recorded.

Richard

 

[Sniper260]

You will find the best time for load development and testing is early in the mornings when its calm and cooler

 

[RTH1800]

About shooting in mirage. It seems to me that mirage "boils away". What that means to me is that I never chase it. For example, if it is going up and right, I simply find the lowest position to the left that the bull shows up and wait for it to come back.
I am an entirely untrained field shooter. Guys like Rob and Frank, as well as online training can more correctly address this. Lower scope power may reduce the apparent effect as well.
RTH