Bring a large pot of water to a boil. Add 1 tablespoon of Kosher salt and the dry shells. Cook the pasta until al dente, following package directions.
While the pasta cooks, roughly chop the olives and eggs. I like chopping them into big pieces, but this is a matter of personal preference.
In a large bowl, combine the drained tuna, chopped eggs, olives, red onion, and celery. Set aside.
Once the pasta is cooked, rinse it under cold water until fully cooled. Drain well and add to the bowl with the tuna and veggies.
In a separate small bowl, mix together the mayo, mustard, lemon juice, garlic powder, pepper, and chopped dill. Taste the dressing and add a pinch of salt if needed. Pour the dressing over the salad and stir until everything is well coated.
Serve right away or keep chilled until ready to eat.