Double crossbow + gravitybow + vital strike?

[Kefler]

Amn i right in thinking that a double x bow , with gravity bow cast on it , and useing vital strike would be 8d6 dmg?

doble x bow starts at 1d8 x 2
gravity bow makes it 2d6 x 2
and vital strike makes it 8d6?

also what damage is added to the second bolt of the double cross bow?
weapon spec? deadly aim? etc etc?

[Kierato]

I would say vital strike to the second bolt is a "no". Vital strike is kinda like precision based damage, IMO. I could be wrong, though. Any non-precision based damage is added to the second bolt, so yes and yes.

[HaraldKlak]

I would be inclined to allow it. Even though you can get to 16d6 with greater vital strike, I don't think it will be any problem compared to a full attack with a bow.

They don't get to take full attack actions, as crossbow mastery only lets the two bolts be reloaded as a move action. Adding in the fact that you take -4 on the attack rolls, have to spend an exotic weapon feat, and burn a feat on rapid shot that you cannot use, I think it sums up to part where vital strike got to be allowed if the weapon is ever going to be used.

Somehow it fits my idea of a crossbow better than crossbow mastery solution, which just turn them into bows. I prefer them as slower, but packing more of a punch than bows (hopefully this will not start a debate on the velocity of arrows fired from bows compared to crossbow bolts).