Help with mirage!

T

Tikka223

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Folks, I was out shooting the other day in 30'C+ weather with very little wind. As a result, there was a heavy "boil" mirage that was making the target look like it was dancing all over the place in my scope. I'm thinking this is was caused a lot more vertical dispersion in my groups than normal. Does this make sense?

Any tips on how to combat mirage?

Here are some photos of some groups shot at 300m. The first few groups were fine but then I couldn't even make out bullet holes it was so blurry;

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I moved in to 200m hoping things would get better, only marginally;

B448ED58.jpg
 
Not sure about the vertical dispersion but I was out yesterday and would shoot a 5 shot string and the barrel never seemed to really cool no matter how long I left it. I started to get it also. It was crazy hot out. I think the FPS might pick up a bit with the heat as the barrel might constrict a little. Just conjecture on my part but when I was shooting through the Chrony the speed started to pick up a bit near the end. Maybe that lends itself to the vertical dispersion?
 
It was crazy hot out. I think the FPS might pick up a bit with the heat as the barrel might constrict a little.
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....interesting notion... However I would suspect ambient temp has more effect on your ammo then your barrel.
 
Adjust the mag on the scope so the mirage is perceptibly less. The mirage is still there but it will enable a cleaner target picture. The advantage of using a variable scope.
Using a mirage band on your barrel will reduce the effect of heat off the barrel.
You look to be using 1" dots - these are going to dance around like beans on a hot plate on a warm day. You may be imperceptibly chasing these on the target. If you use a larger aiming spot and quarter it with the reticle and less magnification might be an effective strategy in extreme heat.
Adjust the powder charge to accomodate the effects of the heat on the load. This may take several attempts on different days to determine what load will be effective.
 
Yikes...

Did you have the sun shade on the scope?

Next time lay a piece of lightly folded note book paper on the barrel In front of the lens and see if it helps... Try a lower mag and if in doubt reconfirm your group at 100m just to make sure it's not your ammo playing tricks on you...

The next obvious tip is to avoid shooting on such warm days where cold beer and lots of shade are clearly a nicer way to deal with the heat :D
 
dryfire said:
Using a mirage band on your barrel will reduce the effect of heat off the barrel.
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Right on...

No one can effectively read the hot barrel mirage... if you are not using something over your barrel, you are handicapping yourself.
 
Oh and a Mirage Tube is NOT what to use. If you have one on your scope remove it and toss it away. They hold the heat in.

Go to Staples and buy one of those clear plastic desk pad covers. Cut them about 2.25inches wide. Then run over to C-Tire and get some of those sticky velcro round buttons to stick on your barrel and on the plastic strip.

Works like a charm.

In the shortrange BR world we learn to use the mirage with our fixed power scopes. Can't dial it out with fixed 45X scopes.
 
How about increasing the aiming mark to about 22" and install a good set of iron sights, use about a 3.5 mm front insert. :p Then read the mirage in your spotting scope:). While your at it ditch the bypod grab a heavy coat, a sling and a padded glove and really enjoy the hot days:D. We need more nutz shooting TR and that new rifle should work well. See ya on the range;)
 
KDX said:
Not sure about the vertical dispersion but I was out yesterday and would shoot a 5 shot string and the barrel never seemed to really cool no matter how long I left it. I started to get it also. It was crazy hot out. I think the FPS might pick up a bit with the heat as the barrel might constrict a little. Just conjecture on my part but when I was shooting through the Chrony the speed started to pick up a bit near the end. Maybe that lends itself to the vertical dispersion?
Click to expand...

Bores get bigger as they heat, not smaller. Its like when the old time blacksmiths used to heat the iron rim of a wagon wheel to expand it, then cool it into place.

Barrel heat and ambient temperature can do plenty to raise pressure and velocity though.
 
I think my poor shooting ability may some how be related to my less than ideal groups.
 
Will have to try that plastic anti-mirage band idea. I've also always wondered if dialing out the magnification to 10x or 12x would reduce accuracy. I always thought aiming at a smaller target makes you focus more and shoot tighter groups.
 
The past several days around here have had pretty calm evenings. When the air is dead calm, or very close to it, you will get "barrel mirage" happen after you fire a few shots. Not only does it make your sight picture very, very "muddy", it *also* causes the apparent position of your target/aiming-mark to shift. So you are tricked into aiming each shot at a slightly different place, which hurts your group size, often quite badly.

With even just a bit of wind, the stagnant hot air is blown away and the problem largely avoided. A field expedient fix can be to "wave" or "fan" the air away from your barrel (this is more easily done by a helper than by the shooter).

Note that barrel mirage is a different effect than what we ordinarily refer to as "mirage" when we are shooting (ordinary mirage is in the air between your muzzle and your targets). Opinions vary as to whether or not ordinary mirage will or will not cause an apparent shift of your aiming mark.

In outdoor highpower shooting, we don't usually see barrel mirage; it's only in exceptionally calm conditions where it'll happen (and this is more likely when you are testing ammo in the evening). A mirage band or a mirage tube are used to deal with barrel mirage when it arises. I find it interesting that cycbb486 says that mirage tubes don't work; that the first time I've heard that, but knowing that he is a serious BR shooter I am inclined to pay attention and ask for more info on that...
 
R1200GS said:
How about increasing the aiming mark to about 22" and install a good set of iron sights, use about a 3.5 mm front insert. :p Then read the mirage in your spotting scope:). While your at it ditch the bypod grab a heavy coat, a sling and a padded glove and really enjoy the hot days:D. We need more nutz shooting TR and that new rifle should work well. See ya on the range;)
Click to expand...

I was going to suggest he use apertures but I didn't want to scare him off !;)
 
Tikka 223 like Daniel just said there are 2 types of mirages barrel and true mirage , I was shooting for a while tonight between 7 and 8 and there was no mirage at all tonight with absolutely no wind , it was cloudy .

All I can tell you is in N-B with the very high humidity levels we have seen this week if the sun comes out it's instant mirage unless it is quite windy, as soon as a cloud rolls over it disapears.

The best thing to do is turn down the magnification until it goes away , mirage will screw up your groups if you shoot in the boil.
 
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