Well the Army considers anything moving 600 FPS or faster as potentially lethal. Meaning shot placement would be what counts.
Now I know a bow goes much slower then 600 FPS, as well as other lethal projectiles. But basically that is the speed at which any projectile no matter the size could be lethal.
Once you factor in the weight of the AA's which yeilds a high kinetic energy, I would say yes that thing is potentially lethal. A smack to the head or face would probably kill you.