I hunt a lot with a revolver and I tend to stay in the 5 1/2 to 7 1/2 barrel length. For me it's the right balance between accuracy and portability. If it was my backup weapon then it would have no longer than a 4 in barrel (depending on your state regulations).
I killed this deer:
last year with this revolver: (it's on my right hip just under my shirt)
It's a fixed sight 5 1/2 Ruger Vaquero .44mag.
I'll be using this revolver for the up coming gun season:
It's a Ruger Super Blackhawk Hunter .44mag with a 7 1/2in barrel. I opted for a scoped model this year for some extra distance as I will be hunting in a different location with longer shot possibilities.
You really don't need anything over an 8in barrel in a hunting revolver.