Colorado Cajun
It is my feeling that they could be used close to 200 yards - IF - everything were to present itself properly.... the biggest factor being the external forces that work on a bullet after it leaves the muzzle. Only you can actually be the judge of that.
I have not shot an elk with one as I am still using Noslers, but as i have said before if the Noslers continue to climb in cost - I would not hesitate switching to Gold Dot.... although I think Cayugad actually found a Speer that might be better for elk. It is a .458/300 grain Uni-Core bullet, a bullet built for the 45-70 specifically the Marlin 450
http://www.speer-bullets.com/ballist...il.aspx?id=127
Here is a ballistic sheet for a 300 grain Gold Dot. The numbers might help you decide...