I figured out how to consistently QUICKSCOPE In this game and I will explain roughly the timing and way to perform this.
The method to doing it is a quick, fluid motion, like wavedashing, and there is an efficiency to it.
The only thing about it, though, is that it is all or nothing. You can't make your gun partially accurate. its either centered, or the spread is equal to hipfire. It involves no breath.
So, Steps:
1. Attatch the VARIABLE ZOOM onto the L96A1 (my preferred sniper. The Psg1 is inconsistant when doing this for some reason).
2. press YY
3. Scope in and wait JUST A MOMENT.
4. Zoom in with your scope by pressing the right joystick and immediately fire.
Explaination: When you scope in, it starts in a random place. When you press YY, it is supposedly more consistent in being centered. The reason you can't just press YY is because of the immediate sway of the sniper and the general inconsistency that comes with the hipfire accuracy during the first moments of scoping in. When you press YY, it seems to center it enough, and then when you zoom in with the variable zoom, for some reason it ignores the sway.
If you go to my fileshare, you can see a nice little clip of me using this for the first time (I had a better one that I couldn't find).
Things you should know:
You don't have to press YY. I don't even know for sure if it makes it much more consistent. It just seems to work more for me when I press it.
Practice this a little. I went to nuketown and tested it out on walls. It is consistent and fires in the same place when you time it right.
It doesn't hurt to wait a second after you scope in.
When you first spawn, you should switch your variable zoom to the third setting. This lets you know where your crosshairs are in a much more defined matter.
If you're killing multiple people in a row, you might catch yourself in a situation where you zoom from the third setting into the first and get a kill or miss, and then you have to shoot from the first setting which will be much less accurate.
