Heat a cast-iron skillet or griddle over medium-high heat until very hot. Working in batches as needed, cook pork and ham in the hot skillet, turning halfway through, until warmed and slightly crispy, about 2 minutes. Remove from skillet; keep warm.
Return skillet to medium-high heat. Cut each bread loaf in half crosswise. Working in batches as needed, toast bread in the hot skillet, cut sides down, about 1 minute. Divide pork and ham evenly among bottom roll halves; top each with 2 Swiss cheese slices and 2 pickle slices. Generously spread roll tops with mustard; add to sandwiches, mustard side down.
Brush skillet with 2 tablespoons melted butter. Add 2 sandwiches, bottom sides down; brush tops of sandwiches with 2 Tbsp. melted butter. Weight down with a heavy skillet, pressing slightly. Toast sandwiches, turning halfway through, until bread is golden and cheese is melted, 6 to 8 minutes. Repeat with remaining sandwiches and butter.
