Deployed sniper/nerd in the Middle East here... thought I might throw some more science in the ring. Hopefully, I'm not too late to the party.
I actually had to do a few experiments to find solutions to problems like this in graduate school. I think what you were experiencing at the match is a combination of factors but can primarily be chalked up to the tricky effects of heat distortion, driven by reflection and/or refraction (essentially a speed change). I’m going to just jot down my train of thought and hopefully, you can use some quick math and confirms your findings.
Addressing the direction of refraction and reflection: The image as the observer sees it can reflect and refract.
View attachment 8188078
Light passing from a less dense to a more dense medium bends toward the normal(N), and vice versa. Now, I don’t know where you were in relation to the sun and target, but since the image refracted or reflected the light down, and you held too little of DOPE, we can surmise there was a significant difference in air density between your shooting position and the target position. You just happened to be situated right at a barrier below the density line of two parcels of air…
The heat distortion effects are caused when light is refracted through air of differing densities. Hot air is obviously less dense than colder air, so light waves are bent differently in hot versus colder air toward what is called the normal, or the idealized 1:1 refraction through a medium with a 0-degree path shift. The result is visible heat waves when there is a significant temperature difference between the ground and the air above it that will bend the light path to the observer by up to 90 degrees! However, that is not super relevant here, as light rays bend 1.33 to normal in just water, or about 33% from the medium to the observer. Results can even be seen as an even larger shift at a greater distance and more angular perspective (the difference between elevated platforms and prone is significant).
So, let’s see if your results are within an expected refraction angle through presumably not perfectly dry air, and not submerged in 100% water. It would be helpful to know all your DOPE and weather data to really calculate this thoroughly, but we can roughly assume and estimate your angle of refraction to be between 1% and 33% (i.e. refraction angles of light--> Perfectly dry air = 1.0 and Water = 1.33).
Since we know light can appear upwards of 33 degrees off the actual straight/normal path to your eye, we simply need to see if your correction was within ~30% of your DOPE…. definitely are assuming your DOPE isn’t 3 mils or higher.
A DOPE of 1 mil would have an adjustment of up to < 0.3 mils
A DOPE of 2 mils would have an adjustment of up to < 0.6 mils
I'd wager given your DOPE, your correction was within 10% of it.
So, it all depends on the severity of air density, temperature, humidity, engagement angle, and distance! It really is one of those situations where you can’t possibly be completely precise without all the data… and the match lords certainly won’t give you everything. I think it was just an extra complicated stage due to environmental factors…
Hopefully, this helps and didn’t make it worse.
Peace from the Middle East