Shiney brass makes for more Xs.
It works like this. A shiney piece of brass will press a smoother surface onto the sides of the bullet. When such a bullet is then fired, it becomes subject to external forces and one of those is the impact of photons being reflected from the target face.
The white outer rings, being white and therefore reflective, put pressure on the bullet in flight and tend to push the bullet toward the center of the target where the black center is exhibiting a lesser or, if you will, a “sucking effect” by its absence of reflected photons.
Shiney (smooth edged) bullets are affected more uniformly than dull (bumpy edged) bullets and, hence, bullets made shiney by shiney brass are more likely to strike the X ring.
Interestingly, the white of the “X” in the center of the X ring does, however, tend to deflect shots. That’s why hitting the *exact* center of the “X” is so rare.
This is nothing new, however. The Lone Ranger knew of this property and, therefore, reserved his famous silver bullets for bad guys whom, as we all know, wear black and therefore attract shiney bullets.
Hey, it’s a joke!
Is that why Zurick takes a Sharpie and blacks out the X?
My thought is that quantum mechanics comes into play — the nth shot knows where the n-1th shot went and tries to follow the same path.
Another effect I have seen in high-power shooting is that the spotter affects the sight picture. I suspect pasters do so, too. Our club was using 3″ spotters at 200yds while NRA regs call for 1″ or less. I have asked for a golf tee to be used as my spotter to reduce the effects on my (admittedly fuzzy with age, pre-cataracts, etc.) sight picture.