[stelug]

I couldnt follow well the wole thread but about the impact point I can tell You that if You visit any ancient museum here in Europe You will find out that ancient roman slingshot bulletts (I intend the slingshot made by two string and a pouch, the one David used against Goliath) where never round. The shape was at losange (trapezium) because the stabilizing effect after few meters flyng. The air pression on the belly (fat) center part will make one point flayng straight forward and the other pointing back. The same concept applied to catapults darts wich, unlike the bow's darts, did not had any kind of feathers because to flight straight thei only relay on the fused shape.

Hope was enaught clear

 

[stelug]

I can speack for direct experience. When I was teen with my crew we had the hobby of collecting car's stems (fiat, alfa, lancia, morris). Collecting means that we where patrolling our quartier with a screwdrivers in the pockets ready to steal those little piece of art from cars. I know was not smarth idea but we wher young. matter is that after few days most people where rearly hangry and started a sort of man hunting against us wich was going to end rearly bad in a no exit road. I had been lucky enaught to stop the first aggressor with a shoot in a leg with my natural fork slingshot with square rubbersand a perfect round river stone. I have seen this man walking rearly bad for more than two week after.
BTW. I am not proud of that bat is very far