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Occasionally, a rifle may even shoot groups that shrink with distance, when measured in moa.
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I've never heard of one that'll do it consistantly. If there is such a bunch of bullets loaded that do, then they all have special properties that change their direction back towards the down-range group center. And they all know not only where they are amongst the trajectory paths of previously fired ones but which way to change their trajectory; down, up, left, right and combinations of each one. Such bullets are truly magic. The faster ones must slow down a bit so they don't strike too high down range; the reverse must happen with the slower ones so they don't strike low. Most interesting is how the ones on one side of the trajectory paths horizontally.
And if it's the rifle that's causing this to happen, how in the dickens does it make the bullet change directions?