5 - 11 Figure 5-8. FORMULA FOR COMPUTING SIZE OF CHARGE TO BREACH CONCRETE, MASONRY, AND ROCK P = R3 Where– KC P = TNT required (in pounds) R = Breaching radius (in feet) K = Material factor, which reflects the strength, hardness, and mass of the material to be demolished C = Tamping factor, which depends on the location and tamping of the charge 5-10. TIMBER CUTTING CHARGES. Table 5-6 shows timber-cutting charge sizes. Figure 5-9 through Figure 5-15 show the types of charges and the formulas to use with each. Table 5-6. TIMBER-CUTTING CHARGE SIZE Figure 5-9. ABATIS