I can tell you now if you've been paying attention, many of the 6.5mm firearms use Caseless ammunition, which does not eject shells at all.

I have seen shells eject from non-caseless weapons but none on the ground afterwards.

because i havent see all of those weapons in real life i can't tell witch drop out shell, but on those weapons i talk about can be seen a shell ejecting hole. Why do you make holes if the shells didnt eject on out it. check the guns. i dont have time to looking for after every weapon what is in the game.

About the eject shells staying on the floor, imagine five sections in a meeting engagement, thats around 50 blokes. Each fires two 30 round mags and each section has a machine gunner that fires 200 rounds.
You've got almost 4000 spent casings on the ground.
Now imagine the sheer amount of polygons in them, not to mention the physics calculations.

Asaob, yes they have the ejecting hole because you can use ammo with cases. But since it's using caseless nothing is being ejected.

anyway the shells can stay on the ground, just need to add it a maximum counter like bullet holes. Try it on a wall shoot as much as you can on same wall. And you will see the earlier holes will dissapear. Anyway arma 2 had a mod for this purpose i bet if they dont make it the modders will do

We are very sorry, this issue was closed as designed.