Hot Shot [Head Graze] -> Dot x# of enemies [Reload], 1-2 [Reassemble]-3-1 [Quick Reload]-2-3 when there are 3 enemies is what I do on MCH for trash pulls. Throw in Raging Strikes + Blood for Blood (+Hawk's Eye when I get it...) after the Hot Shot for bosses. Remember to pop Head Graze off cooldown (unless you have something to silence) as it's low CD and gives some extra damage oGCD which adds up. Anything more than 3 mobs and AOE "rotation" (Hot Shot, multi-DOT, spam AOE, repeat) is better damage-wise until you get lower on TP.

Depending on how much the other DPS are trying, I'll be higher or lower than the "traditionally" higher DPS classes. Sometimes the odd tank will out DPS me randomly, but then again I also have seen my SCH out DPS DRGs before so it's not something to be too concerned about. Things will still die more than quick enough for random dungeon purposes. Honestly, anyone who is expecting flawless play out of people using the new jobs 30-50 aren't the types of players you should bother concerning yourself with.

DISCLAIMER: I have a lvl 36 Mechanist, so I'm by no means an expert.