Since it can stack up to four times for 10 seconds, you need to fire aimed shot followed by arcane shot basically back to back four times. But it doesn’t seem you’d have enough time to get the stack going since aimed shot takes a while to cast. Is this just a spec that requires full benefit from later specs of the MM talent tree?
Never seen this stack to 4 in my life. 2 is commin, 3 is lucky