Sun and Mirage (need explanation/help)

[AJ Peacock]

Although I've shot a bunch and done action type competitions, I've never done any rifle competition. I've noticed a few times (yesterday for example), that Mirage was having an impact with my groups.

While the wind was blowing (10-12mph swirling), I was shooting 1/2moa and better groups with my 338am yesterday, all horizontal. Then when the wind stopped, but the sun was bright and shining right on the target, my groups changed to 1/2moa all vertical.

Do you all think this was Mirage? I was shooting at 200yds and it was near 90 degrees and bright sun. I could see the shimmering of the target at times, and other times I couldn't.

Anyone know of a good reference/reading material for me on this subject?

Thanks,
AJ

 

[Boss Hoss]

Ahhh yes --- the wind and mirage can be your friend! Send me a PM and I will email you a document that will help you master this little problem!

Dave

 

[AJ Peacock]

So I guess at 200yds Mirage can move the group 1/2 MOA? or More?

I sent a PM, thanks.

AJ

 

[dogdinger]

id like to read that also [email protected]

 

[Boss Hoss]

You have mail--I have sent this to everyone that sent me a PM--if you did not get it let me know.

 

[Boss Hoss]

Ok---have sent emails to everyone except one. Asked for a email addy from him but sorry for the late response from Friday---was out shooting getting ready for my elk hunting trip on friday!! 4 more days!!!!!

 

[royinidaho]

AJ,

It's great that you are shooting a rifle well enough to see this and to catch on so quickly. What Boss Hoss will send you will serve you well.

Back in my benchrest days I set out to learn the magnitude of the effects of mirage. I was shooting a 40X 222 Light Gun w/a 26X Leupold (or was it a 24X) either way it would shoot along with your AM out to 200.

I knew the range very well. Bare dirt and a few weeds between the benches and target. Mirage was brutal, normally. Newbies there would shoot around 3/4 MOA until they caught on.

I set up @ 100 yds well before sunrise. As soon as the 100yd target was visible I fired a sighter to verify zero. Then fired fired for score, so to speak.

I shot one shot every 30 Minutes until 10 O'clock. Compensating for the wind with each shot. I recall wishing that I could do such a good job with the wind during a competition.

Result: a real nicely space group of shots nearly perfectly vertical for a length of 2 inches.

Set your scope on its highest power and get it solid on the bags and centered on a small dot at your distance. Touch nothing and watch that dot do the dance. Then be grateful for a rifle that shoots so well even without knowing about mirage. Then you'll start seeing some "good" groups.

 

[Boss Hoss]

Ok--cleaned out my in box again and anyone who did not get the attachments emailed to them send me another PM as I just sent some more.

Dave

 

[Len Backus]

Dave, if you email me I will upload it to this thread if you like.

 

[eddybo]

Mirage is an amazing thing to me. I love to sit a rifle in my rest with the cross hairs aimed at the bullseye early in the morning. When you come back 2 hours later and the mirage has picked up, the crosshairs are off target. Its also cool when the mirage is really kicking and you have little gust of wind that clear the air to sit there and watch the crosshairs move up and down or left and right even if the gun is sitting perfectly still.

I have seen the mirage so bad on my friends range that the cross hairs would jump from below the mothball to over the top of it 30 or 40 times in a minute, but the mirage would never boil and the wind flags were hardly moving at all. I couldnt do anything with those conditions. My buddy shot back to back ones in it. When your a newbie and see someone do something like that it makes you realize how much you have to learn.

AJ at 200 yards mirage can definately move the POI more than 1/2 MOA. Mirage can also tell you more about what the wind is doing at your target than most would imagine.

 

[AJ Peacock]

Eddybo,


Thanks

AJ