There are pictures of his shooting house and test range in the book, take a good look at them before making any conclusions about no mirage effect. What you do versus what he did or anybody else does are completely different.

Mirage will eat your lunch. Dont squeeze till the target sets still and looks round like it does when you hold it up close. SLW

I'm working my way through "The Bullet's Flight From Powder To Target", and it ain't easy. Franklin Mann discusses mirage on pages 177-180; describes his testing, and concludes that "...no mirage could be detected, in slightest degree, to affect telescope lenses or change the position of cross hairs on target up to 200 yards."
I've read the section many times, and think that I understand what he said and what he did.
His conclusions seem to fly in the face of the conventional wisdom concerning mirage. Could all the more recent work that I've read about shooting in mirage be wrong?
joe b.

Mr. Mann is absolutely wrong in his conclusions! However, a low amount of error in weather deciphering before a shot might not make much difference for score contests having large "bullseyes". Group shooting needs all of the low distortion power the scope manufactures can provide to see the real "weather". But, that's a catch-22 because a powerful scope limits the field of view, blocking the coming weather change from which currently is in view. I personally don't shoot group competition anymore because I have realized over the years that I'm not the weatherman required to win a meet often enough. A weather man will always outshoot a shootist, when everything else is equal between the contestants. ... felix