You can get the location of any selected entity with Game Value: Location. Grab a game value item from the values ingot and right-click while holding it to see options. Shift + right-click while holding it to choose targets; if you're getting the location of a projectile involved in an event, you can use the Projectile target. If not, you'll want to select the projectile using the Select Object block, then use the Selected target in the game value.