Particle-laden gravity currents are driven by the density difference between a heavy fluid-particle mixture and a lighter ambient liquid. Natural and industrial situations often involve the release of a finite volume. In this chapter, we revisit the finite-volume “dam break” configuration of a particle-laden suspension in the laboratory, in order to provide a detailed description of the early moments of the flow (the slumping regime), with respect to the relevant dimensionless parameters. A total of 288 runs using three different lock-release devices and two-fluid numerical simulations allow us to cover a large range of particle sizes and densities, volume fractions, bottom slopes, and geometries. By tracking the front propagation through time, we extract the dimensionless slumping velocity Fr and dimensionless characteristic slumping duration τ . Slumping velocity increases with the bottom slope but decreases with the particle volume fraction when the latter exceeds a critical value. Above a critical Stokes number (the ratio between the particle settling velocity and the characteristic current velocity), τ decreases as the Stokes number increases. We derive scalings and energetic balances that reproduce the observed trends, confirming the role of energy transfer from the initial state toward the slumping phase on the resulting dynamics. This initial process and its characterization remain crucial to prescribe relevant initial conditions for large-scale predictive modeling.