Mirage

[joeb33050]

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.

[Dusty Miller]

I ain't never heard of no "shooting in mirage".  Whatsit?

[haroldclark]

Mirage.

If I understand the statement in your question, the person asserts 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 have played with the study of Mirage for the past 3 years and 2 days a week.  The Mirage is an interesting phenomenon.  Mr. Mann is somewhat right about the 200-meter distance of 200 yards.  However, it would depend upon what you are shooting.  Mirage raises hell on a 22 Long Rifle at 200 yards.

What is mirage?  Mirage is a series of wavy lines in the “Air”.  The lines may move right, left, upwards or in any degree of angle from the earth surface.  When the Sun is shining on the earth, the surface is heated.  The heated earth creates wavy lines going straight up as the heated air rises from the surface.

If there is a slight wind, the mirage will go from straight up to the direction the wind is blowing.  It may appear to be horizontal in a heavy wind or at any angle covering the 180-degree flat surface of the ground.  It can reverse direction in a moment without considerable notice.

A fast moving bullet will still be subject to the disturbance that we see in the Mirage.  Actually, the reason that the Mirage is moving other than straight up is the wind.  The wind will affect the path of a bullet to a degree, depending upon bullet weight and velocity.  The mirage does not actually affect the Point of Impact.  The cause, that makes the mirage move, does in fact cause a different POI of the bullet.

When you are reading the Mirage for left to right movement, you are in fact determining the severity of the wind affect on the bullet travel.

Mirage and elevation:  This is a tricky subject and a lot of people may not agree with me.  As I have declared, I have spent several years spotting for numerous caliber TC Contenders, Encores and rifles up to 45-100 BPCR.  I have made a study of the effects of Mirage.

Example:  Let’s say that the mirage appears to be rising at a 45-degree angle to the right at 500-Meters.  The mirage is best read with some kind of a background, like the Target Rail, that is black or a dark color.  The mirage reading says that the wind is blowing the vertically rising heat waves sideways and makes them appear at a 45-degree angle to the right.

Now, lets really talk about what a mirage is.  A mirage is an image created in this case by the heat waves and the wind blowing it.

When I first started noticing what the mirage was telling me, we had been shooting all morning at 500 meter Rams and punching them dead center with 308s and 7mm Mausers.  The temperature was cool and comfortable.  We took a lunch break and exchanged lies for about an hour.  We resumed shooting and the perfect shooting rifles are now hitting 2 feet high and a foot to the right of the Ram’s head.  Out of absolute frustration, I held the POA at the foot of the rear leg.  The ram was facing right on the railroad rail stand.  I hit the Ram high and slightly right of dead center.  My buddy did the same thing and had hits too.  

What happened?  The sights had not changed during lunch, but the heat of the day changed and the wind from the left came up.

My theory on this situation is that the Ram didn’t duck or move, but the picture (Mirage of the Ram) moved with the rising heat waves that are being blown right at a 45-degree angle.  If you aim at the Mirage, you will, in-fact shoot where we see the Mirage Picture.  When the wind blows strong enough from the left, the mirage lines will spread severely and appear to be moving sideways.  In this circumstance, you are fighting the Mirage and the Wind.  I have held as much 8-feet left with a slow moving 30-caliber bullet (2000fps).  Did a 10 mph wind move the bullet 8 feet or some portion there of?  Or is it a combination of the Picture Mirage moving and the wind also affecting the bullet drift?  I personally, think it is both.  If I know my firearm or another person’s arm, I can look at the mirage at 500 meters and call your POA for a hit, depending on the reading.

Two days during the week and 2 additional Saturdays a month, you will find me at our shooting club.  I shoot and my buddies continue to hone their skills at reading the mirage and wind.  They shoot and I spot for them.

We have done the 1,000-yard Black Powder Cartridge three-day match and I spotted for two shooters.  Using my stated theories above, they came in 2nd and 3rd place in the State Championships.

I do not proclaim to be an expert in this field, but I have paid attention and have made a sport of spotting and calling shots for myself and other shooters.  It is an art form, much to my dismay.  I would prefer that it was logical so I could analyze and make a calculation from my findings.  Well, that is not happening.

I hope this has been of some help to you.

Harold Clark

[Duffy]

Good explanation Harold!
At one time years ago I was told that the bullets "rode the heatwaves" and figured that was BS. Later found out that the heat waves actually bends the light and creates the mirage which makes more sense. Add a bit of wind and it really gets interesting. First time I experienced it we were shooting at 600 yards with a 308. The guy spotting told me to aim 2.5 feet to the left of the bull, I thought he was nuts but it was dead on. The next shot there was no waves and it was a straight on shot. Third shot had to be held 2 feet to the right and it made for a pretty nice group. Wouldn't have belived it if I hadn't seen it.

[haroldclark]

I am glad to hear that you experienced the 600 yard shots.  It is wild and spotting for another shooter has become a sport in itself with my shooting buddies.  Only 2 of them actually work at it and the others declare it is too much work and too much math.

I frequently tell new observers not to tell the story when they leave the range.  Like I mentioned earlier, I was holding 8 feet right at 550 yards to hit the Ram.  I was shooting a cast 173 grain flat nosed bullet with a Ballistic Coefficient of "None" at 2000 feet per second.  The wind was severe, but consistant.  Also, I had the width of the Ram for slack in my guess of left hold.  I had two new shooters there watching and I was calling out my point of aim each time to my partner.  I told those old boys that if they told what they saw here today, no one would believe it, so spare yourself.

Harold Clark

[Duffy]

I have messed around with crosswind tests using my 45 colt and that's interesting. Behind my shop I have a clear shot  1/2 mile field and on a windy day (15-20 mph) I lobbed some out to around 500+ yards. Using the impliment tracks as somewhat guides some of those slow moving bullets were moving over as much as 50 feet or better.  It was a learning experience and quite fun to try and outguess the breeze.

Ryan

[haroldclark]

That thought brings to mind another adventure with wind and etc.  One day I was shooting my favorite 30-06-cast bullet rifle at 420-yard turkeys.  That day, we were experiencing a headwind of about 7 to 10 mph.  When the wind is from left or right, the rifle will hit all targets out to 550 yards with a 173-grain cast bullet with the correct windage call.

However, between the firing line and the Turkey line is a 20-foot Burm backstop for the 200-meter chicken line.  On the backside of the burm it is angled up about 45 degrees.  When the wind blows from behind the burm, the wind is compressed until it launches upward.  When my bullet crossed the burm, the upward motion of the wind would give 19 or more inches of lift to the projectile.  If the wind ceased, I could hit the Turkey.

To further confirm this action we aimed at an object that was away from the burm, yet out to 375 yards.  At that target, I shot a 5" group with the headwind.  I shot at the 420-yard Turkey and shot 19 inches high on average.  I then turned to the 330-yard pig line with no burm in front of it and knocked down pigs without difficulty or sight changes to compensate for the wind.  Of course, I set my sights for the pig distance before shooting.

When there is a tail wind or wind from behind us, we experience the same, but different, lift from the front side of the burms.  That story has yet to be verified in inches fo bullet travel.  It still makes me crazy trying to figure out what to do.

Keep reading the wind and mirage.

Harold Clark

[Duffy]

It's those kinds of challenges that keep your brain from turning to mush!  
Some of this may explain why when we were kids and shooting at a 2X4 waaay out there we sometimes swore that the bullet veered around it. At least it looked like it hit directly behind it in the dirt!

Ryan