General

Around 685k range assuming you have the full empress set and the bowguns are scrolled perfectly. (dex % is up to your discretion)

[quote=soulfist]@above

I do like 430-500ks on bosses (crit). 146% boss and 147k range. Add maybe 25% boss and 25k range and you should do 600s, 30k range and boss and it should be relatively consistent.

Edit: I have [b]69%[/b] pdr, I do about the same on Horntail/Czak.[/quote]

*looks at bolded text*
LOL RAND. Keep that pdr%

I would say 600k range.

@above

I do like 430-500ks on bosses (crit). 146% boss and 147k range. Add maybe 25% boss and 25k range and you should do 600s, 30k range and boss and it should be relatively consistent.

Edit: I have 69% pdr, I do about the same on Horntail/Czak.

Probably 450-500k, really depends though.

Close to 500k range.

I've heard it's about 600k on average mobs?

For your reference: 130k range just touches 200k crits on normal mobs (Edit: actually from this info, simple maths tells me that 650k range will get me max damage).
If it's on a boss, then... you can do the maths.. Consider Boss's pdr(v) and boss % on your equips(^)

Not 100% sure but I'm estimating about 500k range on critical hit to be able to hit max dmg on normal monsters.