Yeah, it's random on who you'll get. Sometimes it's hard to leave the voip thing on with some players that are pretty odd lol
The hit detection is strange, but it's deceiving on how the bullet spread goes - the aim point stays still always (unlike most shooters) but the bullets actually climb up as the recoil clicks in. It usually means that people tend to aim for mid-body mass, and then the bullets 'climb up' and get a head-shot. If you crouch for stability then ironically you'll get head-shot a bit more.
The AK and M4 single first shot is deadly, but after that I'm finding it crazy spray time - with the bullets hard to see. I spent a round or two experimenting with a wall at different distances - it helps show where the bullets are really going, as it sure ain't the aim point
I've also seen a few 1 vs 1 new players rotating around each other on full auto, guns blazing away with neither of them hitting anything from about 5 feet out - they think their bullets are going where the aim sight is, but they've climbed up about a foot above the enemies head once they left the trigger down for too long. The real pros (not me, I'm fairly useless) spend a lot of time climbing the mouse down to concentrate fire