Shots Fired: A Machinist Guide

[Myon88]

buff order for single target opener is written as bfb>he>rs>hc; it should be HE+BFB>HC>RS. putting RS 3rd means you lose it for 1 GCD during wildfire; putting HC 4th does not get you any benefits over putting it 3rd

To expand on this, the reason HC is the 3rd buff activated during the pre-pull is because that is the earliest you can activate it and still get the maximum utility from it (5 charged shots).
BFB, HE, HC, RS, Tank pull, Hot Shot...

If you activate Hypercharge and have the turret immediately attack, you'll notice you get your 5th charged shot on the ~13th second of the buff, and the last 2 seconds of the buff don't do anything at all because it drops off before you would have gotten your 6th shot on the ~16th second. To get a clear picture of this, just go to a target dummy and watch the buff on the turret for yourself, while counting the charged shots it fires during Hypercharge.

When you pre-activate HC as above you're basically frontloading that 2 seconds of wasted time, and if you go to a target dummy and look at the buff closely, you'll see you now get your 1st charged turret shot on the ~3rd second of the buff, and that last 5th shot comes right on the 15th second just as it drops off. This deactivation timing is also favourable because when Hypercharge drops off right as the turret fires its last charged shot, it immediately resets the attack swing and causes it to fire a normal shot.

However, because the timing is so tight, it is critical you make sure you're getting that first Hot Shot off ASAP to put yourself into combat and cause the turret to attack. For example, if your tank is slow to pull after you've popped your buffs, or the tank pulled and you didn't Hot Shot fast enough.

I'm sure you can see why this is bad, if you do the sequence normally you already barely get that 5th charged shot in before the buff drops off. If you're slow to get into combat on top of that, it means you'll get your first turret shot later than normal, and you're definitely not going to get that 5th charged turret shot now as Hypercharge will fall off before that happens. You lose 1 charged shot worth of damage, your raid gets less vulnerability uptime as that 5th shot would have refreshed the debuff on the boss, and you lose the favourable deactivation timing for a further DPS loss.

Again, these things are best seen in person - go to a dummy, pop your pre-pull sequence of buffs and see how long you can wait before entering combat, before you only get 4 charged shots instead of 5 under Hypercharge.