I've looked but haven't seen mention of this anywhere (I didn't look too hard though). 
 
When you zoom in with the sniper rifle you can pause the action with the power wheel (RB). While the action is paused you can still aim your rifle and line up a headshot. Then quickly release RB and press 'fire' (RT). Who needs adrenaline? 
 
Has anyone else found this or use it? I admit that I rarely use it since I'm playing as a soldier and have adrenaline rush already.

I do that with the shotgun right after charge.

I never even thought of it. Cool tip!

"I never even thought of it. Cool tip! "

It's a good idea, but seems kinda annoying, always pausing before you shoot.

ha, never thought of that. sure it's useful to someone.

You don't really need to do this an Infiltrator with your Passive skill, it goes into bullet-time when you zoom in for the first few seconds.
 
Also this tactic seems kind of cheap...

You could do this in the first game too.

I pause the game to line up biotic powers and such, but on PC I don't find I need any more time than I already have to line up a headshot.  In most cases I can line up 90% of the shot before I even break cover/look down the scope.

" I do that with the shotgun right after charge. "

I do it all the time with standard weapons, but I didn't know you could still do it with a sniper rifle.  
 
Thanks for the cheap tip!

I think I exclusively went for the rifles, until it ran out of ammo. To me though, the whole fps nature is ruined by constantly pausing the game for this trick, you can line up headshots pretty easily anyway, It's not like the first shot will miss. It's a sniper rifle, aim for the head and spend points on damage upgrades. Once you get the widow, you can take out freaking any enemy (minus the dudes with barriers and armor) with one headshot, you're just cheapening the game with this.

 
How did I never think of that? Thanks!

I find my suit never has enough ammo pockets for a good amount of spare ammo.
Come on Bioware, Garrus and shep want bigger ammo pouches.

I think allowing the user to pause the game and adjust their aim specifically allows for strategies like this. When you are low on health and the next shot will kill you, the pause and line up shot trick can save your skin countless times.