>>64077628
>but the bigger problem is that projectiles that hit near the edge of composite helmets tend to blow out the side rather than being captured by the material,
That is more concern for big projectiles like pistol bullets. But who really cares about pistol protection for helmet?
Most real threat is small fragments and they easily embed themselves into material.

>but not the best choice to outfit a whole army.
It all was figured 2000 years ago. If want bothe coverage and convince of use for helmet you need moving flaps.