Has anybody done a write-up explaining all the geometry and physics behind homemade slingshots? Here are the assumptions and observations I've come up with (obviously for maximum power!): 1) Theraband gold only contracts at 150m/s, so no matter how strong you make the draw, your projectile will never move faster than this (without effectively making a compound bow, and using lever arms to magnify the speed... which isn't really a slingshot anymore) 2) Because speed is your limiting factor, to get the most energy delivered to the target, you must go with the heaviest load possible e.g., a 1/2" lead ball @ 150m/s will have twice the energy of a 1/2" steel ball moving at 150m/s 3) The height of the forks, without a forearm supporter, will limit your draw power, because taller forks make a longer lever to pull against your wrist with. Therefore, you want to have the lowest forks possible, yielding the highest risk of hitting yourself. 4) The width of the forks limits your maximum velocity, as the further apart they are, the less the rubber is pulling in the direction you're firing. For maximum efficiency, you must have the most narrow forks possible, also yielding the highest risk for hitting your hand/slingshot with the ammo. Am I right in these observations, and assumptions? Questions: 1) What do you guys use as extra heavy ammo? Cast your own enormous lead balls? I was thinking of taking some 1" (or greater) iron rod, and cutting it into 1" long segments, yielding a somewhat suboptimal cylinder, instead of a sphere... I can't imagine it'd be worth the time and difficulty trying to file it round, though. Large steel nuts (for bolts) were also a consideration, as they're readily available, albeit an inappropriate shape for accuracy. 2) What has better penetration for soft, and hard targets? Is lead, at twice the energy, but much softer better, or is it better to use steel, as it won't deform, at the cost of possibly ricochetting? I supposed if you were hunting small game (rodents), it wouldn't matter, but lead would be more lethal, and not penetrating the entire animal and ruining the meat would be an upside, but for larger game, say, um, a possum or racoon, the steel may be better, as you'd be trying not to crush the entire animal to kill it, but penetrating to hit vital organs. I suppose the best idea, which likely isn't worth anyone's time, is to make full metal jacket lead shot. Also, how about penetrating hard targets, like plywood? I'm thinking lead would be better. Thoughts? 3) What is the benefit to tapering the bands towards the pouch? Seems like you're just cutting away rubber for no reason to me, and losing power and durability as a result.