why do people think that the sound in the zed promo is a gun shot???!!!

It has the sound of cocking the gun before the sound goes off so it's easy to assume that it's a gunshot

Probably because of that text line that reads "Dead Eye". That title is definitely associated with firearms. I however think it could be either.

It could be a gunshot that procced Thunderlord's..

But what about a gun that shoots thunder?

I heard a gun shot.

I imagine it to be more of a bolt of somekind of energy.

There is a cocking sound that implies that it is a gunshot. But idk. There r more teasers to come that will explain everything.

It's Lightning Shen

It's not just the Zed teaser anymore. Sona's teaser clearly has the same pumping/cocking sound before the gunshot. If it were a thunder clap (which sounds pretty similar to a gunshot imo) there would be a low rumbling beforehand as opposed to the cocking/pumping sound.

Nah.

In reality, it is the sound of a powerful gem, crackling with energy.

Vigor intensifies