Place the pinto beans into a large container and cover with several inches of cool water; let stand 8 hours to overnight. Or, bring the beans and water to a boil in a large pot over high heat. Once boiling, turn off the heat, cover, and let stand 1 hour. Drain and rinse before using.
Bring the neck bones to a boil with 4 cups of water in a large saucepan. Reduce heat to medium-high; simmer 20 to 30 minutes.
Pour the drained beans into the simmering water with the neck bones; add additional water to just cover the beans. Bring to a boil over high heat; reduce heat to medium-low, cover, and simmer 1 hour. Make sure that the water level continues to cover the beans as they cook; use more water as needed. After 1 hour, stir in the shortening; continue simmering until the beans are tender, about 30 minutes more.
