Hate to burst your bubble but an 180 gr. bullet, regardless of what it is made of, will have the same energy and trajectory as any other 180 grain bullet of the same ballistic configuration. Depleted uranium is heavier than lead but if you are using a 180 gr DPU bullet it will have no greater energy upon impact than a 180 gr lead bullet.
A copper bullet which is dimensionally identical to a lead 180gr bullet will have less mass. A copper bullet with the same mass as a lead 180gr bullet will have to be larger.
Sorry, your bubble is the wrong bubble. What I was referring to was one of the same volume and shape as the same bullet standard for the FMJ mentioned. Thus the weights of the same bullet shape for various metal densities will vary widely. That is why I stipulated the same impact velocity, which zeroes out considerations other than the fact that the FMJ-sized bullet weight would be different for different metals of construction.
That is also why I did not introduce the trajectory of getting to the target, which is far more complex than you indicated, as any handloader, hunter, or sniper would know. My Lyman 47th (Edition) Reloading Handbook takes 18 pages of fine print to just barely cover ballistics and trajectory variations, and 183 pages of tables for reloading various calibers, bullet shapes, and weights. If you wish this to be in the discussion, you have a much bigger task than your model suggests.
Do you begin to recognize why I said, "There is more to this than the average citizen would understand"?
Respectfully --