This is my traditional opener rotation, but I do change it up from time-to-time to fill in for new scenarios.
-Fletchette Round
-Shoot First
-Blaster Whip
-Dirty Kick
-Sabotage Charge
-Sucker Punch x2
-Fletchette Round
-BackBlast
Unless the target is a tank, or has a healer friend, it's dead by this point.
The reason I use backblast so far down into the rotation is because of Fletchette Round. It's a very powerful DoT, so I want to make sure it has maximum uptime. If I used Backblast further up into the rotation, it would reset Fletchette Round before it finished ticking, therefore nerfing your DPS.
5k Shoot Firsts are theoretically possible... but not likely to happen very often unless you have a Surge Adrenal ready. It's a rarity.
Again, to clarify, this is a maximum damage rotation that doesn't account for enemies that start moving, casting, healing, whatever. If an enemy does anything except sit there and look pretty, you'll have to improvise with your other abilities.