This is a heavier weight lunar hammer designed to chip a sample of rock off a larger rock or to drive core tubes into the lunar soil. When attached to an extension handle, the hammer was also used to dig surface furrows. Hammers of this style were used on Apollo 14, 15, 16, and 17.
This particular hammer was used for training, and was transferred to the Smithsonian from NASA - Kennedy Space Center in 1974.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.