A lot of people say that using a gun instead of a needle to pierce your cartilage will shatter your it, is it always true, or I it very rare?

A needle will not shatter cartilage.

A gun might, although as you said, this is rare, but it happens. To be safe use a needle in a clean piercing studio. The men and women may look a bit intimidating at first, but they know what they're doing and they're very nice!
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