Night mirage

A

alinwa

oft dis'd member
Anyone have any experience with shooting at night? I shoot out a window. Temp inside around 65F, outside around 45-50........ I get very consistent conditions many nights but WEIRD mirage effects.

My thought is that it's the air flowing out my window. Target stays crystal clear, image is sharp and black, no 'lines' nor 'waves' in the air..... just a target that creeps hither and yon.

I've been working days and having to tune at night. Last night drove me nuts. I don't know if I made any headway A'tall. I'm tempted to throw a known (old) barrel back on with a known load except that last match I lost a shot.

Any tricks for tuning in the dark?

al
 
al,

Back when I shot prone smallbore, our range had covered mounds & 12' walls at the side & back. In (what we call) winter, for a couple or three weeks, we got this strange effect which we finally identified (saw thru our spotting scopes) that there were two horizontal layers of air meeting right on our targets. As these layers bubbled & seethed (like those water beds that were popular a decade or three ago) they threw shots above & below the bull out to an 8 on the UIT (ISSF) target.

Any chance that you have a similar issue?

JOhn
 
JOhn I dunno.

I just got random shots, no pattern, and when I set back and just watched through the scope the target would wander back and forth, up and down, about 1/8" @ 100yds. But the shots would actually show air in the groups.... it's as if 1/8" of visual produced 1/4" of actual dispersion.

???

I do not get this effect when it's raining. Only still dry nights.

al
 
If you haven't already...

try a long mirage tube....one long enough to reach nearly the end of the barrel and make sure the muzzle and tube are beyond the window frame.--Mike Ezell
 
Try setting up outside and come back and tell us what you see. That should tell you something about your theory.
 
Warm air exiting your shooting port causing mirage in the cool night air?
Warm air exiting the top. Cool air entering the bottom.
Entirely plausible I would imagine.

Maybe a fan blowing outward in another window to reverse the draft? Maybe not optimum shooting conditions but a quick way to see if the mirage disappears.
You may end up walling off your shooting bench to allow it to remain a consistent outdoor temperature whilst still enjoying the warmth at the reloading bench.
I really wish I had these problems Al:cool:
 
Many years ago . . .

alinwa said:
Anyone have any experience with shooting at night? I shoot out a window. Temp inside around 65F, outside around 45-50........ I get very consistent conditions many nights but WEIRD mirage effects.

My thought is that it's the air flowing out my window. Target stays crystal clear, image is sharp and black, no 'lines' nor 'waves' in the air..... just a target that creeps hither and yon.

I've been working days and having to tune at night. Last night drove me nuts. I don't know if I made any headway A'tall. I'm tempted to throw a known (old) barrel back on with a known load except that last match I lost a shot.

Any tricks for tuning in the dark?


al
Click to expand...

Al, sorry - I don't know any tricks . . . can only report on my own anecdotal experience shooting in sub-ZERO night-time conditions. Frequently, the COLDEST nights are the most 'calm' - thus, I decided that, if ever I was going to shoot ZERO groups, it would be in this 'dead-calm'!:eek::D So, one time, years ago, on a -15 F night, I set up a target, got up at midnight and started shootin' - bullets ALL over the target!:eek: I decided that the mirage was INSIDE the [warm] scope . . . so, I left the rifle outside for a couple of hours, and repeated the test - with the same dastardly results! NO further night-time -15 F shooting was needed to convince me of my flawed logic!:eek:

Shooting during the dead-of-night, even in mid-summer, has always proven vexing - as John pointed out, I believe THAT may be due to air layers of differing temps., at about target level, which occasionally switch positions!;) I have seen the target image move well over a FULL ring (1/4 inch @ 100 Yd.) in these dead-calms . . . it's spooky business! )chill( RG
 
Did you ever notice stars twinkling at night? Guess what you see as twinkling? It's called heat waves. The night sky is colder than any surrounding objects. The second law of thermodynamics still apply, heat travels to cold. So needless the ambient atmosphere is disturbed by rain or snow you will see it most of the time Heat waves moving or rising is all so known as mirage. I could go on with this subject for a long time but I think that should give you a feeling for the depth of the problem.
 
Mike ...

mwezell said:
try a long mirage tube....one long enough to reach nearly the end of the barrel and make sure the muzzle and tube are beyond the window frame.--Mike Ezell
Click to expand...

And the purpose is to trap cold or hot air inside that tube? What's the theory behind this suggestion? Art :)
 
al,

The mirage tube begs an interesting question.

Did the target start jumping before or after you started shooting?

John
 
Al,

Been there, done that, and have experienced all of the related problems mentioned by you and the others on this thread.

My findings and solutions may differ from others, but this is what I experienced and some of the variables I tried to control.

Ambient temperatures had to be nearly equal inside and out. In my case, I shut the heat off and left the window open until equilibrium was met. The same goes for your rifle.
A mirage tube helped, but wouldn’t eliminate the problem.
If it was the middle of the winter and there was a huge difference between interior and exterior temps, I couldn’t reach equilibrium and couldn’t shoot.
If you shoot in the summer, you have to take care the ground cover or the ground itself doesn’t absorb so much heat that it continues to radiate upwards thru the night. I shot over grass and hay fields. If I cut my hay and the days were sunny/hot....I couldn’t shoot again until some regrowth occurred.
Your target illumination must be far enough away to not heat the air at the target or any point in between.

Landy
 
I wondered why I missed that big buck the other night, I mean day:D:D.

Al what part of Washington you from, I used to live in Woodland, logged for 9 years up the Lewis River. Marc
 
Hey Marc, I'm down by Yacolt/Amboy maybe 20min from Cedar Creek Hole on the West slope of Yacolt Mtn. Woodland is where a lot of our work has been in the last few years.

The upper end of the North Fork is HOME :) From Spencer Butte to Mitchell Peak, Huffman's Cabin to the headwaters of Clear Crick the elks and cutthroats are in big trouble from us sidehill gougers.... we've camped up there for 25yrs. Our wives used to go up ahead of us to find a place, leave a note on the Pine Creek Boulder...... they'd be somewhere from the Slides to the Lahars on The Plains Of Abraham to Curly Crick Falls....



A record King run coming this year in the North Fork. Springers look to be HUGE.

I can drive up the hill from my house about a mile and look straight onto St Helens from the south side. Big as a house, looks like you could spot the climbers......

:)

al
 
OK,

I just came up from shooting (hungry) and as darkness fell my groups just went sidewise..... I'ma' go back down with a known PPC and see whats up I think.

I've been shooting in the dark for the last three years but never this particular condition. Normally I do it when it's raining or snowing or even wicked cold but never in this cool clear dryness from a sunny 65degree day to 45 at night.

It's just flat-calm and maybe 20degrees cooler outside.

I think Husker nailed it....I think it's mirage from the warmer ground as the cold air moves in....... I've got a continuous flow out the window and a full barrel mirage shield, this is just creepy-crawlie different. It's like the air between me and the target is shifting all over.

Night Gremlins :eek:

al
 
OK, thanks to you guys I think I got it figgered out....... I figgered out that I just threw away about a hunnerd dollars of the best 8" twist 6mm barrel I've ever touched..... not to mention components.

It is mirage.



I shot known loads.

I put another fan in the window.

I shut down and moved the (lighted) chrono.

I extended my mirage stuff with cardboard trying for isolation.

While I was out taking down the chrono a nice little breeze blew in, YAYYYY :), I stood in the yard checking the flags........ just getting a feel for it........ waiting for the gremlins to clear out........went back in and set down on the scope and HOLEY TOLEDO!!!!! It looked like a friggin' CAMPFIRE!

I took Boyd's advice and went outside, away from the building.

Running swirling dancing mirage. No more "slow mirage" it was/is just plain old bouncy-bouncy but no consistent springback.

I packed it in.

bummer.

thank you all for the ideas.

al
 
Al

I shoot out of a heated building all winter here in Iowa. I have a fan that sucks the air in past the bench and exits at the far end of the 25' building. I also use an old target for a mirage tube that reaches outside. The hot air going out the window is usually the problem. If i forget to turn on the fan, or not completely close the door next to the bench---i know just as soon as i look down the scope. Mirage all over.

Sunny days and snow suck too.

Later
Dave
 
Last edited:
Dave Coots said:
I shoot out of a heated building all winter here in Iowa. I have a fan that sucks the air in past the bench and exits at the far end of the 25' building. I also use an old target for a mirage tube that reaches outside. The hot air going out the window is usually the problem. If i forget to turn on the fan, or not completely close the door next to the bench---i know just as soon as i look down the scope. Mirage all over.

Sunny days and snow suck too.

Later
Dave
Click to expand...

Agreed Dave..... but feel I've got this aspect covered. I've been shooting from this position for 3yrs now in rainy and cold weather. I know all's about the frozen trigger finger. Sometimes I put a rag on the Farley handle :)

It's the warm days and cold spring nights that are getting me. Tonite I started in about two hrs before dark.... BUGholes......

I worked up great matching loads with RL-17 and H4350 and started playing with the tuner.

About mid-dusk (no lights, clear target) The air on my face got cold and I started getting the side-to-side heebie jeebies.... shot a few caterpillars while my Begg's Wind Probe gave me the finger and my flag tails hung limp....... and just at dark got the added vertical component.

I'm convinced it's the warm ground just giving it up to the cold air rolling in. Remember, I'm in WA on the side of a mountain. When the thermals come down it drops temp like 20degrees in 10 minutes. I took Boyd's advice and went outside last nite. No joy.

It's just that I've gotten lazy and complacent.... I KNOW this range..... but not this Spring condition I'm finding. (Traditionally I'm WORKING in the Spring and never shoot this time slot much...)

Warm days and cold nights..... I don't think I can get around this one :(

Guess I'll hafta' just shoot the daylight hours for a while. Or wait til 9-10:00PM to start.

I agree that sun on snow is brutal! UN-shootable.

al
 
Al

alinwa said:
.... I KNOW this range..... but not this Spring condition I'm finding. (Traditionally I'm WORKING in the Spring and never shoot this time slot much...)

Warm days and cold nights..... I don't think I can get around this one :(

Guess I'll hafta' just shoot the daylight hours for a while. Or wait til 9-10:00PM to start.

I agree that sun on snow is brutal! UN-shootable.

al
Click to expand...

I think you answered your own question. You usually don't shoot in the Spring. Sometimes at my range in the backyard wierd things happen. Anyone that knows me says---ya right, wierd stuff always happens around Coots--but anyhow my range is on the East side of a 300 foot high bluff. There are times when at the end of the day, when the wind lets up--things get goofy. Bullets go to wierd places. The tails on a couple of my wind flags will lift to 45 degrees and just stay there, no flutter or any sideways movement, kinda like they are frozen. After serious thought, i head for the shop and open a cold one, clean my gun, and quit. I know my limitations.

Like you say, know your range. Good luck.

Later
Dave
 
You must log in or register to reply here.
Back
Top