Avoid using acids on brass. It eats the copper molecules but not the zinc and turns them black if left for too long. A long alkali rinse helps to neutralize the action but the damage is done and the cases weakened.
Tumbler or ultrasonic is a matter of choice. I prefer tumbled for four hours including a while with metal polish added.
Seems you're into old style shooting HaresEar, BP catridges, 130 yo m/l. I wonder whether the m/l is smooth bore or rifled.
“If a cricketer, for instance, suddenly decided to go into a school and batter a lot of people to death with a cricket bat, which he could do very easily, I mean, are you going to ban cricket bats?” :- Prince Philip said after Dunblane