Suggestions for "best" sheep hunting caliber ... 200 to 350 yards?

[MCMXI]

That photo is amazing - where was it taken? Most likely the puma was going after the sheep at the time of the incident.

IIRC, the photos were taken in Glacier National Park. This photo shows the lion with fur in its mouth so you're correct about the circumstances.

 

[RDA 226sig]

I guess maybe I am a little dense or maybe I don't hear too well but I have never heard a game animal complain about having been taken with too much gun. Some guns may be impractical for the hunter to carry but other than that if the shooter can make a clean shot using a magnum for smaller large game is fine. You can have too little gun but on goats any center fire rifle that can produce a good trajectory out to 500 yards will get the job done. A nice little 7-08 would carry great but it is really a personal preference thing.