Employee was changing rigging on a box beam that was to be carried to hoisting bay. Beam was lowered to floor by rough terrain fork lift. Beam rested on rods through the beam holding anvil beams. The box beam slipped 1"" to 2"" on the rods resulting in pinch point between the shackle and box beam. Tip of employees right idex finger was pinched requiring 4 stitches.