[sargon]

Regarding "2 sets of gunfire sounds", an ex-soldier said on FR earlier that you have the sound coming from the source of the firing—the report of the rifle—and you also have sounds as the supersonic bullets arrive and impact with various materials, causing "cracks" which are heard "instantly" (because the sound doesn't have to travel anywhere, essentially).

That alone can lead to "2 sets of gunfire sounds", so such observations aren't as cut-and-dried as one might think.

I'm no ex-soldier, but it does make perfect sense that you'd have 1) the report from the gun at a significant distance which takes some time to reach the target—certainly slower than the bullets—and 2) the "local" sounds the bullets make as they impact concrete and other dense materials in the target area. Viola! 2 sets of gunfire sounds.

Just my 2 cents' worth...

[\/\/ayne]

Regarding simultaneous gun fire, two other possibles for a lone shooter: 1. Echo from one of the tall buildings and 2. He could have been shooting a rifle from each hand.

[SE Mom]

My son was infantry in in Iraq and told me same thing. He says one would not believe the ways sounds of various firearms can get distorted and fool the hearing.