The A-Bolt shotgun is known for being possibly the most accurate production shotgun when shooting sabot slugs in the world. So usually you only need one shot. But it can be very handy and comforting to know you have a couple of rounds ready to go in your spare magazine. Plus, you get the piece of mind that by carrying a spare you won't inadvertently turn your A-Bolt shotgun into a single if you misplace your primary magazine.