7-08remAre we talking about 6.5mm or 7mm 120 grainers?
The 120s have the same jacket thickness as the 140s. The 7mm-08 was a go-to for silhouette shooters and they needed a heavier jacket to knock down the targets. I have killed pronghorn and large whitetails past 520 yards with the 120s outof 7mm-08s.
Not sure as to performance on sheep as I have not been fortunate enough to chase them.