Weighting the assembled sandwiches helps to soften the bread and compress the layers, so the sandwiches are easier and neater to eat.
Brush cut sides of halved bread loaves with oil from jar of roasted peppers. Dividing evenly, layer bottom bread halves with roasted peppers, salami, cheese, and arugula; top with remaining bread halves.
Wrap each sandwich tightly with plastic, and press: Lay wrapped sandwiches on a baking sheet. Position another baking sheet on top, and weight with heavy canned goods or a large skillet. Let stand for one hour, pressing down occasionally with hands.
Refrigerate wrapped sandwiches until ready to serve, up to 1 day. To serve, cut into wedges.
When using store-bought roasted peppers from a jar, don't discard the flavorful oil they're packed in; brush it on bread, as in this recipe, or drizzle over salads and mixed roasted vegetables.