Using a 2 step macro for an arcane mage isn't neccessary - they are faceroll. I'm not sure why you put barrage in your macro. The only time I feel a mage should use it is when they are moving in order to maintain dps. Also, I like to save my CDs for when I lust, as you get the most out of them.

/stopmaco [channeling]
/castsequence Arcane Blast, Arcane Blast
/cast Arcane Missiles
/cast Arcane Missiles
/cast Flame Orb