Re: Heat Mirage From the Barrel
OP,
There could be a multitude of errors here. The only thing for sure is that your bullets hit in the direction the barrel was pointed. If you had called your shots you'd already know if mirage off the barrel had an effect on your perception of aim, possible, but not likely. The big problem with mirage off the barrel is that when severe it can make the target seem to disappear. That's more a problem though with irons than with an optic. As suggested, a mirage band will mimimize the problems associated with mirage off the barrel.
Remember too, there are 4 things that effect trajectory and mirage is not one of them. These are gravity, drag, wind, and temperature. I'm not saying mirage will not interfer with the shot, it certainly can alter your perception of aim. But temperature, ambient, as well as ammunition, and barrel temperature are all certainly suspect here; and, just a 20 degree change in ambient temperature may raise or lower velocity 50 feet per second. 50 fps is worth about one MOA.
As an LR Service Rifle competitor, I'd like to shoot a load which is insensitive to ambient temperature, as well as at the chamber. I have not found it yet. Using iron sights I have a hard time holding for an X-ring hit. An insensitive load to temperature changes, where ever found, would be welcome. BTW, I'm shooting Re-15 which is as insensitive as I've known but not perfect.