[js1138]

How many civilians have heard both a rifle shot and a pistol shot aimed in their general direction? How do you tell the difference?

[tractorman]

I can't answer for the average civilian but my experience is that a rifle shot goes KA-BANG and a piston goes bang.

[Shooter 2.5]

Smaller the bore the higher the pitch. Shorter barrels of the same caliber are louder. The amount of powder is in relationship to the volume. Sonic booms sound like breaking a wooden dowel.
The description of a .223 sounding like a rock falling on a tin roof is accurate.

[Chemist_Geek]

How many civilians have heard both a rifle shot and a pistol shot aimed in their general direction? How do you tell the difference?

I've never been on the receiving end of pistol fire, but semiautomatic rifle fire sounds like, to me, crack-THUD. Drop a bag of potatoes on a wood floor after throwing a paper snap firework down. The crack is the sonic boom of the bullet passing, and the THUD is the sound of the rifle mechanism.