The weight reduction encoded in this type came from the Coinage Act of 1853, which slashed silver content across the subsidiary coinage after rising bullion prices made it profitable to melt coins at face value. The half dime had been disappearing from circulation almost as fast as it was struck. Congress acted, the Mint added arrows to mark the change, then quietly dropped them after 1855 — leaving this transitional type with the reduced weight but none of the arrows that originally announced it.
The weight reduction encoded in this type came from the Coinage Act of 1853, which slashed silver content across the subsidiary coinage after rising bullion prices made it profitable to melt coins at face value. The half dime had been disappearing from circulation almost as fast as it was struck. Congress acted, the Mint added arrows to mark the change, then quietly dropped them after 1855 — leaving this transitional type with the reduced weight but none of the arrows that originally announced it.