Improving DPS on MCH?

Hello all,

I do about 1800-1850 DPS in A9S and I've been told that this is very bad. This is my gear: http://ffxiv.ariyala.com/YWLT

Aside from the lolshiregun my gear is in pretty good shape.

My group takes about 6.5 minutes to kill the A9S boss and when I look at other groups on fflogs they are killing it in 3 minutes or so which is half the time. Not only that but MCH in the top 100 are doing upwards of 3-4k DPS, I can't imagine how this is even possible outside of the opener.

I've studied my rotation vs other people on fflogs, as well as looked at MCH guides out there, and my rotation appears to be pretty good.

Somehow their avg casts are doing 1k+ more than mine for moves like split shot, I can't imagine the 275 weapon adding a full 1k dmg to my actions but maybe I'm wrong?

Does anybody have recommendations of things I might be missing?

I'm grasping at straws here, I don't know how people are hitting 3-4k DPS past the initial opener (when I actually can hit these numbers). Once my opener is finished I watch my DPS trickle down until it hits a steady 1800 or so.