To me, he’s responsible for packing the drums well and in a way to prevent damage. I own a store, and any time something has ever gotten damaged in transit, I’ve always taken care of the customer.
Yes, that is what any ethical seller should do. Unless the buyer arranged their own shipping, the shipper (USPS, UPS etc.) is an agent of the seller and therefore the seller is ethically responsible for the shippers actions. A transaction is incomplete if the buyer does not receive goods in the condition advertised. An ethical seller will a) make things right with the customer, then b) seek recourse from their shipper.