Effects of nonfragmenting solid brass bullets (5.56 mm, 3.1 gm, 1.9 cm long, machine-made at Letterman Army Institute of Research) and fragmenting soft-point bullets (5.56 mm, 3.2 gm, 1.7 cm long, commercially made by Hornady Manufacturing Co., Grand Island, NE) were compared when they were fired through soft tissue of the hind legs of five live swine (50 to 70 kg). The swine were anesthetized endotracheally (0.8% halothane) and placed in the supine position with the hind legs extended. Blocks of tissue simulant (10% gelatin at 4 degrees C, molded in blocks 20 X 22 X 47 cm) were placed against the skin at the predicted point of bullet exit. All shots (a fragmenting bullet through one hind leg and a nonfragmenting bullet through the other hind leg of each swine) were fired at a range of 3 m from a rifle with a bullet tract at 90 degrees to the long axis of the swine's body. Bullet velocities ranged from 930 to 990 m/s. Dissections of the bullet tract (through tissue and gelatin) revealed that tissue disruption from the fragmenting bullets was significantly greater (p less than 0.001) than from nonfragmenting bullets. The recovered bullets were weighed. The results showed that the fragmenting bullet lost 59 to 77% of its original weight and the nonfragmenting bullet was the same weight as originally. Recognition of the amount of tissue disruption and identification of bullet fragments in the wounds resulting from the two different bullets should be a useful guide to operating surgeons in selecting the best approach for treatment of gunshot injuries.