Enhanced burning of plasma-ignited propellants has been deduced in recent years from closed bomb pressure traces. The question remains, however, whether the enhanced burning is inherent or possibly the result of propellant grain fracture. To find out, interrupted and non-interrupted burning tests were conducted with cylindrical perforated grains of JA2 and M30 in a closed bomb with a loading density of approximately 0.2 g/cm(3). Both, conventional black powder and plasma igniters were used, and a few tests were carried out with the propellants cooled to -20 degrees C. The plasma igniter was an ablating capillary, and the electrical energy density was about 0.7 kJ/g of propellant. The diameters of the collected grains yielded the actual burn distance at the time of the interrupted burning. The experimental pressure traces and the conventional burn rate coefficients of the propellants were used to calculate the theoretical depth burned assuming no plasma-induced burn rate modifications. From overlapping pressure traces at Several interrupted pressures, and from comparison to the calculated versus measured burn distances, it was found that there is burn tate enhancement during the plasma pulse-but not much once the pulse has ended. In contrast to the JA2 burn rates, both ambient and cold M30 burn rates, deduced from the non-interrupted tests using the BRLCB code, were enhanced even after the plasma turn-off, thus contradicting the interrupted-tests results. However, vivacity analysis of the non-interrupted tests indicated that the M30 grains exhibited increased surface area (possible fragmentation) because of the plasma interaction-an effect that would cause erroneous results from the BRLCB. Indeed, simulation of the noninterrupted M30 tests using the XNOVAKTC code, and assuming partial fragmentation of the propellant charge, yielded vivacities that mimicked the experimental ones.