Example 3: Bulging of a Shotgun Barrel Caused by a Change from Lead Shot to Iron Shot. A standard commercial shotgun barrel fabricated from 1138 steel deformed during a test that was made with a new type of ammunition. Use of the new ammunition, which contained soft iron shot with a hardness of about 72 HB, was intended to reduce toxicity; the old ammunition had contained traditional lead shot with a hardness of 30 to 40 HB Investigation. The shotgun barrel was of uniform inside diameter from the breech to a point 7.5 cm(3 in. from the muzzle; at this point, the inside diameter began to decrease("Before test"curve, Fig. 7a). This taper, or integral choke which is intended to concentrate the shot pattern, ended about 3. 8 cm(1-in. )from the muzzle, and the final portion of the barrel had a relatively uniform inside diameter 0.720 0.7|5 Afte O.71o test s s.705 0.700 0695 Before 0690 0685 00.51.015202.53.03.54.0 Distance from muzzle, in (a) 0850 0845 0840 After 0.835 90830 B825 Before test 0820 0.8|5 08|o 0.5|.01.52.02.53.03.54.0 Distance from muzzle in Fig. 7 Comparison of longitudinal profiles of an 1138 steel shotgun barrel before and after testing. 1000 rounds of a new type of ammunition were fired in the test(a) Inside diameter. (b) Outside diameter After a test in which 1000 rounds of ammunition containing soft iron shot were fired. the shotgun barrel had a longitudinal profile of inside diameter as shown in the"After test "curve in Fig. 7(a). Comparison of this curve with the Thefileisdownloadedfromwww.bzfxw.comExample 3: Bulging of a Shotgun Barrel Caused by a Change from Lead Shot to Iron Shot. A standard commercial shotgun barrel fabricated from 1138 steel deformed during a test that was made with a new type of ammunition. Use of the new ammunition, which contained soft iron shot with a hardness of about 72 HB, was intended to reduce toxicity; the old ammunition had contained traditional lead shot with a hardness of 30 to 40 HB. Investigation. The shotgun barrel was of uniform inside diameter from the breech to a point 7.5 cm (3 in.) from the muzzle; at this point, the inside diameter began to decrease (“Before test” curve, Fig. 7a). This taper, or integral choke, which is intended to concentrate the shot pattern, ended about 3.8 cm (1 1 2 in.) from the muzzle, and the final portion of the barrel had a relatively uniform inside diameter. Fig. 7 Comparison of longitudinal profiles of an 1138 steel shotgun barrel before and after testing. 1000 rounds of a new type of ammunition were fired in the test. (a) Inside diameter. (b) Outside diameter After a test in which 1000 rounds of ammunition containing soft iron shot were fired, the shotgun barrel had a longitudinal profile of inside diameter as shown in the “After test” curve in Fig. 7(a). Comparison of this curve with the The file is downloaded from www.bzfxw.com