Origin of the American phrase getting down to brass tacks

Q: When people prepare to discuss serious business, they often say they’re “getting down to brass tacks.” Why tacks? Why brass?

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GET DOWN TO BRASS TACKS definition

Etymology 101: origin of the phrase get down to brass tacks is disputed.

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What is the meaning of get down to brass tacks? - Question about English (US)

The saying 'Get down to brass tacks' - meaning and origin.

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