It wasn’t all that long ago that if The New York Post published photographs of an aspiring congressman wearing a leather collar and a chain-link leash, his campaign would have immediately been over. Yet that doesn’t seem to be the case for Chris Gallant, the gay, gun-toting former Black Hawk pilot who’s running for Congress on eastern Long Island. He still may not win, but these photos alone haven’t sunk his chances. When he was 20, Mr. Gallant modeled for promotional photos for Mr. S Leather, a San Francisco fetish brand; many of the photos, which capture Mr. Gallant engaged...