For a Bolt Ace the Minotaur or regular double crossbow is an exelent option.
Crossbow Mastery (advanced players guide):
Prerequisites: Dex 15, Point-Blank Shot, Rapid Reload, Rapid Shot.
Benefit: The time required for you to reload any type of crossbow is reduced to a free action, regardless of the type of crossbow used. You can fire a crossbow as many times in a full attack action as you could attack if you were using a bow. Reloading a crossbow for the type of crossbow you chose when you took Rapid Reload no longer provokes attacks of opportunity.
Now, combine this with crossbow training that gives you dex mod. to dmg on one or both bolts+ any other dmg like deadly aim, gravity bow etc. and you are looking at some serious dmg.
on lvl 11 you kan take signature deed that reduces grit cost of sharp shot to 0, and you now use ranged touch on all attacks