I have one, but it's for a mod I work for and it really doesn't fit your specific needs..
456820 is right, I remember seeing that script somewheres...
But, for bullets you would need to go a bit more different way than with RPGs and such due to the 'slight' muzzle velocity differences...
Also, the KozliceShell is not a single bullet but it infact fires 7 bullet 'burst' to simulate (badly) a shotgun...
So you would need to find a way to 'catch' all those 7 bullets and change their velocities individually...