Pulse-triggered combustion instability constitutes a considerable problem in the design and operation of solid propellant rocket motors. Results from an experimental study involving 45 full-scale motor e rings are presented to provide guidance in motor design and a database for comparison with existing and future nonlinear theories. The repeatability of pulse-triggered instability along with the effect of variations in propellant formulation, operating pressure, grain cone guration, motor scale, and motor length were evaluated according to the parameters fraction of dc shift and wave strength. The stability rating of a cone guration based on these two different parameters was not always consistent; the fraction of dc shift was judged superior. It was shown that oxidizer particle size distribution and the presence of a stability additive affected pulse-triggered instability. In addition, it was shown that instability tended to increase with pressure, that cylindrical grains tended to be less stable than star grains, that shorter motors tended to be less stable than longer ones, and that smaller motors tended to be less stable than larger ones.