Theoretical model of metal gap ejection under strong impact loading and its verification

•A theoretical model of metal gap ejection under shock loading is presented. It can estimate the mass and maximum velocity of the material ejected from the metal gap.•The correctness of the theoretical model is verified by experiment and simulation.•It is found that the gap ejection behavior of metal under high pressure is related to the jet incoherence phenomenon, which will lead to the dramatic change of the ejection mass.