 Although proof shots are used in the service proof of barrels before use, the vast majority are used in propellant charge design.Proof shot emulating APFSDS rounds are also used in stabilizing-fin SoD trials, which is often combined with a charge design trial.When running a charge development, or strength of design (SoD), trial, the charge mass and service pressure will gradually be worked up to the required proofing pressure of the weapon system.