Snipe - perfect timing window - IAS

So, I´m playing around snipe and perfect timing, first having assailum (unique helmet) is a must, to have real chance to land the thing, but that is ok, since having uniques, which enables builds are supposed to work that way, the thing that aint ok is, that since snipe locks you in place, you wanna to get it out the fastest you can = stacking ias - I´m at 4,24 attacks per second which makes it fully "charged" roughly in a second. My issue is, that the faster you load it, the smaller the window for perfect timing is, meaning that ias is working against the unique helmet and whole mechanic - (so far it feels like roughly around 4 aps is kinda a sweet spot to make 95% perfect shots.

second thing is, that hitboxes are somewhat wierd, quite often pojectiles go through mobs (or me) even though i´m aiming at standing mob and my accuracy doesnt even show number it just says 100% and thats it.

EDIT: forgot to mention, with this 4.24 aps the visuals kinda breaks, cause when the snipe prompts its time to release, even if i release it at the exact moment, it doesnt crit (and no, its not just my opinion, since i have 8,5 days played time on this char i have the muscle memory for it now so the window for same release time is in 0,1 sec delta each shot)