Target, out of Focus

[Bob Kingsbury]

In the late afternoon, early evening practice, my target becomes
completely blurred. No target hop or mirage that I can see. It comes into focus then out and back in again. Is this a mirage or a capsule of
powder heat that I'm looking through. Any ideas

 

[John Kielly]

Bob,

I'm betting it's heat waves off the barrel.

I shoot a lot of long range belly down stuff & we get that sort of issue when the air is very still even when the rifle is fitted with a mirage shield. Normally, there's enough air movement to keep the barrel mirage away from the scope. Usually, I get a gap where it's clear quickly enough so it isn't an issue. I'm a tad reluctant to shoot thru it.

John

 

[Wilbur]

ditto

to John's post

One of those small battery powered fans blowing over the barrel will fix it gone.

 

[Kent Harshman]

Barrel Heat vs. Water Vapor

Bob,
If you're out again on the range that presents this problem and you haven't had a chance to get one of the fans that Wilbur suggests, try this...when the blurred images presents itself, blow down across the barrel (nothing fancy here, just pretend that the barrel is your birthday cake and you're trying to blow all the friggin' candles out). If the image clears immediately, then John & Wilbur have identified your problem; if not, you may have a water vapor problem on your range in certain conditions...most notably, early A.M., late P.M, when the air is very still, and typically when low light conditions exist (cloudy, no visible sun). Other criteria which can enhance the problem...
1) A relatively narrow range which is completely surrounded by foilage.
2) Any kind of water on your range that you're shooting over (lake, stream, bog, etc.)
Now, here's a disclaimer...before all the "purists" out there jump all over me and say that the proper term is not "water vapor"...call it what you want...the point is, it is related to moisture content in the air and it is heightened by a lack of sun to burn it off or air to "move" it...