5.56/.223 Brass interchangeable

[Unclenick]

Yep. That's how tolerances look. If you have a ±0.002" tolerance, the middle value will be the center of a bell curve distribution and most manufacturers aim at the tolerance being some number of standard deviation from that middle value. If it were, say, three standard deviations, then 68.3% of them would come in ±0.00067", 27.2% would be between 0.00067" and 0.00133" and 4.3% would be between 0.00133 and 0.0020". 0.27% would be rejects. The question is, did you get one of the 4.3% or one of the 27.2% or one of the 68.2%? From a small number of samples, you can't tell. And some manufacturers try to divide that tolerance up into six standard deviations (six sigma) so the rejects come down to one in half a billion. The bottom line is most of the units you get will be closer to the average value than to the end of the tolerance range, but someone, somewhere, will eventually get one at the end of the tolerance range.