The AR-15 is more than a gun. It's a gadget. It's an addiction and the future of firearms manufactures. It's the most wanted gun in America and more than anything it is a symbol of the cycle of fear that drives assault weapon sales.
Like crossbows? Like assault rifles? Got some spare AR-15 parts lying around begging to be crossbowed up? Then the PSE TAC 15 crossbow upper is for you! (video). Or how about this Swiss crossbow that can be cocked in 3 seconds? Alternatively build your own, or even build a repeating crossbow!