Rules on 2nd hand goods vary from country to country. A private sale is still typically classed as a commercial goods import, unless it's a "gift" of nominal value. Most used goods attract a flat rate of around 3% on US import, but state sales taxes can still apply depending on which state you're in. You'll need to check this out locally.
To help you, the international commodity code for drums is 92060000. You will need to declare the purchase price (value) and include shipping costs in that value. Don't be tempted to enter a false value - they often check / compare, and a false declaration will get you in a world of pain.
Any shipping method that uses UPS for the land transport to your address will mean the goods are held at customs until any duty is paid. This can add a week or two to your shipment. Services that use FedEx, DHL, etc, will deliver directly to you without delay, & invoice you for duties later. You may need to provide your tax ID to the shipper. US customs are getting hot on this aspect recently.
Most important - your shipment will need to be packaged such that it can withstand a fall of at least 6ft on to a hard surface. A drum in a cardboard box with a few layers of bubble wrap won't cut it, & nor will it be likely to pass any claim for damage. The bigger the drum, the bigger the risk. Using postal services that ship by sea increases risk as there's many more sorting / handling steps involved. Air is better, but of course, more expensive. I would never ship by sea, & I package drums to bomb proof standard.
Hope this helps.
