Or you can just collect 4 pieces of eliminator set with armor piercing cell and get:
1 Free high impact bolt = excellent filler for ammo regen.
2 Cell charger = absolutely necessary talent for quick ammo regen in pve, but useless without armor-piercing cell.
3 Well, armor piercing. It's not so good by itself, thats true, but pretty usefull with armor debuff from grav round on target.
Demolition round crits for 5k in full rakata gear and costs same amount of ammo as grav round. Its our best nuke atm, why shouldn't we use it?
Dps in pve is all about ammo management and proc timing, and thats also a reason, why alacrity is so terrible stat for us.