Mirage

[Nordnecker]

I've read many posts about mirage effect. I realize heat from firing the gun or hot, bright sunshine can cause mirage.
At any rate, I've got a gun project at a point where I can shoulder it and look down the barrel. The front sight is .090 silver and is easy to see. In fact, it's so easy to see that I was considering not putting a rear sight at all. So, I walked down into the woods to see how the gun would point. It was 50 degrees etc. dappled sun and shade in the woods. To my surprise, I saw mirage while sighting down the barrel. Maybe I need that rear sight after all.
What are your thoughts on this? Why the mirage on a cold, unfired, still in the white barrel? 

[Daryl]

Barrel at room temp  70F (21C) - out into 50F (10C) weather - heat waves off the barrel = Normal.

If you are shooting a thin walled smoothie in freezing weather, one shot from a cold barrel will give
heat mirage.
Taking a gun out of the warm truck- no shots fired - heat mirage, sight of no sight.  With a rear
sight, the mirage will likely be worse. Front sight will appear crooked. Normal and the target is not
where it looks to be.

Higher front AND rear sights will sometimes get you above the mirage. Lower sights will cause more
mirage problems, yet lower sights are  Period Correct - your choice.

We had elastic heat shields stretching from the rear sight base to the front sight of our match rifles as we'd
often fire up to 20 shots on the sighter target and 10 scoring shots on the official target. A heat shield was
necessary due to heat mirage.  Heat mirage was even worse in the winter time & our sights were up to 1 1/2"
 above the barrel. So- it is something that will happen and not much you can do about it - let it cool down.

Then, in the summer time, or late(March/April)winter on a sunny day on the snow) is mirage coming off the ground/snow itself.
So - barrel mirage and ground effect mirage. Both to really mess up your mind.

[Nordnecker]

Interesting. Thanks Daryl.

[Daryl]

Further - barrel heat mirage makes the sights jump, slant or move in the direction of the wind, up usually on about a 45 degree angle off the barrel.

Ground heat and moisture mirage make the target move in the direction of the wind & if no wind, straight up. Pretty much the same as barrel mirage

and both are difficult to shoot accurately in. Much practice is needed & a lot of luck helps too.

Oft times, the wind is moving at a different  speed and direction at the muzzle, than at the target.  The more one looks into this stuff, the greater the headache becomes.

[smylee grouch]

I think Daryl,s observation is spot on. Go to just about any bench rest match and see 4-5 wind flags up for a 100 yd. target.  There can be a total reversal of wind direction in 50 yds. to help confuse you along with that mirage and the scoring  rings change value in half inch increments on some targets.

[snapper]

Try figuring out what the wind is doing at a 1,000 yard match.  There are times that you simply just shake your head. 

Last year at Harris MN, I had 6 or 8 misses in a row.  Simply could not figure out what was going on.

Wind flags pointing in opposite directions.  Trying to read the wind and the mirage. 

Throw in the Coriolis Effect and I almost start to cry.

Fleener

[smylee grouch]

I think the 1000 yd range in Harris is pointing North IIRC. Would you say the coriolis effect, affects you more in the north/south direction?

[snapper]

No wonder I had all those misses at Harris!  I knew it could not be me 

Fleener

[Dennis Glazener]

Mirage can be seen much better thru a scope. Some of the worst I have seen was when the night time temperature was in the 20's (F) and the morning sun was blazing down on the cold ground. Even when you do not see it with the naked eye it's there and will affect your point of impact. Then there is the mirage off a warm/hot barrel to contend with. Sight shades/tubes will help with barrel mirage but you still have the ground mirage to contend with.
Dennis

[smokinbuck]

It oesn't help with ground mirage but I have a couple of target rifles whose barrels definitely give off a mirage, especially in the summer. I put a strip of painters tape on top of the barrel from the front to the rear sight. It doesn't stop the mirage but it does seem to deflect it out to the sides of the sight picture.
Mark

[Daryl]

Try figuring out what the wind is doing at a 1,000 yard match.  There are times that you simply just shake your head. 

Last year at Harris MN, I had 6 or 8 misses in a row.  Simply could not figure out what was going on.

Wind flags pointing in opposite directions.  Trying to read the wind and the mirage. 

Throw in the Coriolis Effect and I almost start to cry.

Fleener

Just in 300 yards, I've seen 3 wind reversals down South, on the Thompson Mountain range. In between the 100, 200 and 300 yard flags showing reversals, the others, 25,50,150 & 250 flags were all over the map.
Of course the worse wind, is point blank - what's going on in the first 100yards.

Then try to figure out the mirage as well.