Ok, stick with me here. We have a handful of projectile weapons... all of which seem to be Minmatar atm for some odd reason except for maybe the missile turrets (not sure on the origin of those, I don't know Eve very well). Anyway, unlike other weapons that have a reason for their ammunition eventually disappearing into thin air, a projectile is a solid object which won't just lose it's structural integrity by flying through the air.

I know what this means, and as much as I hate it, here's the weapons that need to be fixed to make this a reality:

HMG's. And I hate this idea more than any other, but it is a projectile weapon. That of course means to maintain balance they will need to be reworked... good luck with that. I'd make suggestions, but since there is so much QQ over this weapon already I'll keep them to myself.

SMG's. With the crappy aim they currently have, all you'd need to do is increase the spread a little more and it should be ok.

Mass Drivers. I know you hate them, but they are projectiles. Unless you plan to give them a fuse and make the sharpshooter skill determine the fuse length, they need to be made unlimited range weapons.

Missile Turrets. This one isn't really an issue. Missiles have been nerfed hard enough that giving them back their unlimited range can't really make them OP. Maybe back when you could OHK a heavy with one missile they could do with a range nerf, but now that they are basically rocket propelled plush toys, unlimited range isn't that big of a deal. As for drop, it should still have some drop to it since it is a rocket with only forward thrust.

For all of the non-explosive projectile weapons, you can drop off the damage considerably at longer ranges, but the bullets still need to travel until they hit something, be it the ground or the target.

I don't know if I missed any, but feel free to let me know if I did.