How exactly does one get a chamber differing from the tube? Yours talking perfect nonsense.

There is no difference in 223 stamped and 5.56 designated brass. No more than any normal difference between manufactures and lots of brass. The only difference, sometimes, can be the leade between the 2. The 6x45 is nowhere considered in the 223/5.56 nonsense.
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“It isn't so much that liberals are ignorant. It's just that they know so many things that aren't so.”
- Ronald Reagan