The burning properties of propellants are important inputs needed in ballistic simulation. A closed vessel experiment is employed to characterize the burning properties of gunpowder. The results obtained after testing in a closed vessel are exploited according to the development of the burning rate equation defined in the NATO Standardization Agreement. Recently a method for the estimating of the burning rate, r(p), of a solid propellant simply on the basis of pressure P(t), which had been recorded during closed vessel experiments, and a knowledge of the shape and geometric dimensions of the propellant grains, has been reported. This method does not need prior knowledge of the values of the thermodynamic properties (specific force and co-volume) of the propellant. It has been verified on the following examples: a 4/1 single-base propellant with cylindrical single-perforated grains and the JA-2 triple-base propellant with seven-perforated grains. In this paper, this method was corroborated for the case of spherical and flattened double base gun propellants. Additionally, based on the previous cited method, a new approach allowing the estimation of the ballistic parameters was established.