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It's not semantics, it's correct. I never suggested using 5.56 in a SAAMI 223 chamber. Critical thinking time: If the longer leade of the 5.56 allows 5.56 spec ammo to use more powder to drive bullets to higher velocities without raising pressures, it follows that using 5.56 ammo in a chamber with a shorter leade will result in higher, possibly dangerous pressures.

Pressure alone does not equal more velocity. A smaller capacity case loaded to the same pressure often results in less velocity because there is less powder, thus less fuel (energy) available to accelerate the bullet