I have no idea how you came to that conclusion. It is certainly not consistent with any of the information in the provided links or formulas. You have the same simple means to know the mass and velocity of the projectile in either case. Measure them as you would the velocity and mass of any projectile. Neither equation has to do with "momentum transfer" or "energy transfer" or conservation of either momentum or energy. They are both equations for the force applied by an impact. One calculated from energy and the distance of the impact and the other from momentum and the time of the impact. The explanation provided in the link associated with the two formulas explains things quite clearly. There's absolutely nothing in the link that suggests the formulas are about momentum transfer or energy transfer--the word "transfer" doesn't even appear on that web page. As for the "affected mass", basic physics indicates that the force applied to the target is equal to the force applied to the projectile so it's the same force either way. Your comments about momentum transfer and conservation of momentum are accurate--they just have nothing to do with the formulas/links or my comments. My comments and the links and formulas are not about any kind of "transfer", they are about the force generated by an impact (i.e. how changes in energy/momentum relate to force applied and vice versa) and the ways it can be calculated. Bottom line is that projectile impact force** can be calculated from either projectile energy and the distance required to stop the projectile or projectile momentum and the time required to stop the projectile. The formulas are clear, the information in the link is clear, my explanations are clear and they all agree and if, for some reason, you don't like any of those, you can easily find other sources that will tell you the same thing. **Please note that "projectile impact force" is not the same as "momentum transfer" or "conservation of momentum" or "conservation of energy".