For valuation and comparison of the effect and risk of non penetrating projectiles, intended as non-lethal weapons, simple and well-defined test methods and vulnerability criteria is needed. To meet this requirement FOI has designed a surrogate thorax intended to give the same response as a human thorax exposed to this kind of loading. The surrogate thorax permits measurement of, in this context, relevant quantities such as displacement and displacement velocity of the inner surface of the thorax. There is so far no reliable threshold values available regarding lethal injury or achieved effect in human thoraxes. The surrogate thorax however can give a qualitative comparison between different projectiles or projectile designs with respect to the risk of injury. In this report we intend to demonstrate how the surrogate thorax can be used for comparative tests of the effect from non penetrating projectiles and what kind of result that can be expected from such tests. For this purpose the types of non lethal projectiles acquired for the Swedish Armed Forces, Kravallptr 12/70 och 40 Kravallptr, have been tested and compared. The projectile called 40 Kravallptr resulted in twice as large displacement of the inside of the thorax compared to that caused by the projectile called Kravallptr 12/70. This may result in a considerable increase in the probability to stop an aggressive part in his or her intention. The projectile Kravallptr 12/70 showed minor effects on the surrogate thorax and a surprisingly large spread in projectile velocity and a corresponding spread in hit probability. Both projectiles are judged to be non-lethal alternatives. Keyword: Non-lethal weapons, NLW, Non-penetrating projectiles, Blunt trauma