Gag bits are probably Trevor Brazile's last choice, but he's had success with them when a chain or a port failed him in the box.
"There are a lot of different types of gags out there, but the main thing about a gag bit and the success you can have in the box is that there’s no curb pressure," Brazile explained. "A lot of horses will relax in the box or not react to the gates as much if they have confidence leaning into a gag."
When you’ve got your horse comfortable in a gag, Brazile suggests you add a leather curb to it, hitting the horse a little higher on his lower jaw. They might react differently to a curb with a different placement than in their prior experiences, taking away some of the stress from the curb.