Quick question on attachments

What I want to do is play a special effect on a unit whenever it attacks, specifically a muzzle flash on their rifle. I didn't think it would be this hard until I found using searing arrows would not trigger the effect if the target they attack was auto acquired (not player ordered).
I then tried using triggers to play the effect but for effects, like the flame thrower effect would constantly stack the effect that would make the flame thrower still look like it is firing even though the target has been dead for 5 seconds already. This problem also happened with one of the assault rifle muzzle effects where the flash would still be playing even after the target has long been dead.
I then tried using orb abilities but those didn't work out at all.

I'm using the konstrukt attachments if you were wondering - anyone know how to properly play the weapon effect attachments when the unit attacks?

The most foolproof way to do it is to simply model-in the muzzle flash to all of the marine models. If you don't want to / can't do this, the next best way is to use a different effect. Flamethrower effects last a long time. Also be sure that if you are using dummy units, that the unit is killed quickly to avoid repeat effects.

Unfortunately, I have little to no knowledge on how to edit models in order to add the weapon/muzzle special effects to it. Any links to tutorials specific to this would be of great help. For now, I just need a way to play the muzzle flash special fx when the unit attacks and stop playing as soon as it stops attacking. I'm sure someone out there has figured this out

Thanks in advance

Models attached using the sphere ability play their death animation when the host unit attacks.

Therefore, you need an attachment that does your desired effect in its death animation.