I can't give you alternatives, But its a nice, quick, Auction House Option.
With Last Stand not being Magic Based and this has an enhancement to R.acc, and Ranged Attack, Unlike Ice Magian Trial, which would only slightly benefit your Quick Draws.
Erra Also however has Higher Delay = Easier x-Hit Build.
So in the End, Its either - Work on a Magian Gun for 2 Base Damage and some MAB for Quick Draw, Or buy this off the AH For 10k, Which while it has 2 less base Damage, offers a good chunk of R.acc, and focus more on getting your Armageddon in the mean time.
Its far from a perfect gun, but the best AH Gun for COR atm. (Still, Get your Armag or Bedlam :P)
If you don't have the Empyrean or the WoE weapon, the Ice MAB Magian gun is extremely fast to do with Ice weather being constant in Ulegrand and Zvahl.