Coltsville National Historical Park Act - Establishes the Coltsville National Historical Park as a unit of the National Park System in Connecticut.

Requires the Park to provide interpretation and viewing of specified sites, including the East Armory and Colt Park. Requires the Secretary of the Interior to enter into a written agreement with the Connecticut State Library, Wadsworth Atheneum, and the Colt Trust, or other public entities, as appropriate, to gain access to Colt-related artifacts to have them on display in the East Armory or within the Park.

Authorizes the Secretary to enter into cooperative agreements with the owners of any properties within the Historic District or any nationally significant properties within the Park under which the Secretary may identify, interpret, restore and provide technical assistance for the preservation of such properties.

Requires any federal funds under such an agreement to be matched on a one-to-one basis by non-federal funds.

Authorizes the Secretary to provide technical assistance and public interpretation of related historic and cultural resources within the Historic District.

Requires the Secretary to complete and submit to Congress a management plan for the Park with the advice of the Coltsville National Historical Park Advisory Commission established by this Act.