Interesting question birddog.
My original sheep hunt was in 2004. I chose to tote a 300WSM, mostly because I was hunting in Grizzly country and I didn't want to be under-gunned. I used that rifle for 3 of the 4 sheep because I shot it well and it killed lots of stuff. I shot my last sheep, a Stone, with a 6.5 Creedmoor and a 130g Accubond. I was still hunting in Grizzly country, but by then I figured out that my guide would be packing a bear rifle and Sheep don't need bear medicine.
If I ever get to hunt sheep again, I will take my 6.5x284 shooting a very accurate 124g Hammer Hunter.