1. From your Steam Library, click on the game to bring up its library page.
2. Click Controller Layout. It's on the bar with Store Page, Discussions, Guides, etc on it.
3. Click Edit Layout. This will bring up all the keybindings for your controller.
4. Find the Circle/B button and on the right of it you'll see a cog button. Click it.
5. At the top is the autofire toggle. Enable it.
6. Once enable a slider is enabled for setting how much it autofires. It has a default value of 100. Reduce that to 30.
7. You're all set, Carrier-Boy.

Optional: - Make a separate layout just for using autofire for easy layout switching.