What about ballistic coefficient and drag coefficient?

The "closeness" of a bullet to the mathematically "perfect" bullet has to play into bullet efficiency and thus cartridge efficiency at some point. See Krupps Standard Reference Projectile.

There are some basic models out there and I believe they were developed by the Army's Ballistics Research Lab. You've probably seen them in small ballistic programs usually they are called something like G1, G5, G7, etcdrag coeffiecient models.

The short comings of those early models gave rise to the BC or ballistic coefficient, bullet form factorand the sectional density models which helped relate different bullet shapes and sizes to the drag models. Which is why we generally use Ballistic Coefficient as a measure of how much "better" a bullet is moving through the air.

So SD is not the product we want to look at. It's a component of BC which is what we currently use to compare bullets.

Ballistic Coefficient = (Bullet Sectional Density) / (Bullet Form Factor)

I'm sure computational fluid dynamics has been applied to conventional rifle cartridges and there is a model and I'm sure it uses a number of variables to spit out a betterproduct but the question remains: how do you define "better"? Also, what assumptions is your model based upon? The answers, if there are any, have an enormous effect on how and what your model shows, and if those findings are worth anything in the real world.

Also, a complex fluid dynamics model that approached anything relative to real world performance may not even be able to be ran on anything short of a mini-supercomputer. And certainly not a normal PC.

Now that all applies to exterior ballistics.

If you're talking about terminal ballistic performance, no I don't believe there is any model for terminal ballistics. At least one that would produce anything worthwhile or close to reality. The inherent stochasticityand sheer volume of variables of such a model would be impossible to simulate in my opinion.