Last I heard, it was due out last winter...
I am a little supprised to see it advertised...
its not like it is period correct, at all!!! (not that the 44rus or 45sch are any better...)
In spite of what was advertised, I would think they would come out with one in 44mag or 45long colt before doing 44-40.
I think I read somewhere that their actions are limited to around 1.65" OAL for the cartridge.
The action is very solid, though...I think you could drop a 454 in there and not have to worry about overpowering the rifle.
(your arm may fall off, but, the rifle would still function)