Almost every Democrat running for president supports so-called “gun buybacks.” Too bad they don’t work.

Proposals range from Joe Biden’s voluntary gun buybacks to the more radical mandatory confiscation proposed by Cory Booker. (He still misleadingly calls it a “buyback.”) So it’s worth examining how such buybacks played out recently in New Zealand, which passed a ban on the sale of semiautomatic weapons and a mandatory gun buyback program after a tragic shooting in April.