Yes, the hitzone system is already finished. Acknex has this feature, too, at least since A6, it's called c_updatehull and reloads the (invisible) collision mesh from a certain frame. As the function is, of course, pretty slow, you should avoid every call when possible and thus I've made some optimizations: All enemies are saved in a linked list. Before you c_trace, I iterate over all enemies and check if they are close to the ray. Then I sort those close entities by distance to the trace origin and update only the collision mesh of the first 3 (any value is possible) enemies.