My post got deleted on my phone. Here it is again.
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For example on some guns like Kimber they are super tight and considered high end. Other high end guns have zero variance in tolerance. The chambers on some of those guns (the few that I've shot) were so tight that if the guy doing the loading at XYZ ammo factory didn't have the crimp just perfect the gun wouldn't work.

Yes they were perfect by spec but practical not as much.

Same story with slide weight or spring tension. Some of the guns are built so good that only one or two types of high end ammo will work in them.

Several other things can be mentioned as well