Step 1

Combine Calabrian chiles, shallot, garlic, both olives, piquillo peppers, oil, capers, vinegar, and oregano in a medium bowl; season with salt and pepper.

Step 2

Do Ahead: Olive salad can be made 1 day ahead. Cover and chill.

Step 3

Split bread in half along the equator line. Divide olive salad, including any liquid, between halves. Lay salami on bottom half of bread, followed by capocollo, provolone, mozzarella, mortadella, and prosciutto. Close sandwich and wrap tightly in plastic. Place between 2 baking sheets and weigh down with a heavy pot or two to flatten slightly. Let sit at room temperature, turning over halfway, 1–3 hours before cutting into wedges to serve.