In this study, we propose an adaptive set membership constant modulus (SM-CM) algorithm with a generalized sidelobe canceler (GSC) structure for blind beamforming. We develop a stochastic gradient (SG) type algorithm based on the concept of SM filtering to facilitate an adaptive implementation. The filter weights are updated only if the constraint cannot be satisfied. In addition, we also propose an extension of two schemes of time-varying bounds for beamforming with a GSC structure where we incorporate parameter and interference dependency to characterize the environment, which improves the tracking performance of the proposed algorithm in dynamic scenarios. A convergence analysis of the proposed adaptive SM filtering technique was performed. The simulation results showed that the proposed adaptive SM-CM-GSC algorithm with dynamic bounds delivered superior performance compared with previously reported methods and at a reduced update rate.