When entering the states through Dulles International do you need to reclaim your baggage and re-check it before proceeding to your connecting flight?

Yes.

Yes, both TSA and United States Customs and Border Protection regulations require you to claim your baggage and make any necessary declarations/claims before moving through customs and immigration and subsequently checking your baggage to then proceed through security.

When arriving in Concourse C you proceed through US Customs and Border Protection without picking up luggage but in any other Concourse (A, B, D, H) you do have to

Yes you do

Sim

Yh