Size of muzzle: B4 OB2 18 4 B3.5 OB1 17 30 B3 R4 16 3.5 B2 R3L 15 3 B1 R3.5 14 29 B0.5 D3 J2 R3 13 28 B0 D2 J1 R2L 12 27 R2 11 26 D1 R1L 10 25 1 24 9 R1 23 8 R0 0 22 7 21 6L BT 20 6 OB4 2 5 OB3 19 4L