Hi,

i am just doing a weapon where i need the ordanence to fly through the enemys and explod only when there it impact on the floor or buildings, and while it flys and goes trough the enemys there should be a trail damage.

You are asking for help, right? If so, only beams have the ability to pass through multiple units, but they cannot support an explosion ODF. And what do you mean by trail damage? Can you provide an example?

ok.

Lets take the bunderbus canon for example. you shoot, the effect goes trought the Units, and explode when arriving an wall, or an other kind of object, that's not an human or droid. while the effect goes trough the Units it endamage them.

Umm, let me break this down. You want to make an ordnance that hurts people, passes through them, and explodes against a wall. Sadly, this can't be done. As AQT said, the only weapons that can pass through people and impact other things are beams, and they can't have an explosion. The closest thing you can get is the sonic gun the geonosians and the imperial officer have. It has one ordnance that hits a unit, and a secondary ordnance that comes later.