300 savage,
The Big Sheeps are very interesting country! Have hunted them a little, but years ago also worked for an archaeological research firm that did a survey on the BLM land. Among other things we found an old, fired, "inside primed" .50-70 Springfield case, which just might have been hanging around since the last of the buffalo hide-hunting days of the 1880s, when that was the last area where a big herd existed.
One other reason the 130 GameChangers might have worked is that while they're long, the plastic tip doesn't count much in stability, because it's so light. Which is why some twist-rate formulas indicate some plastic-tipped bullets won't stabilize--but do. The one twist program I've found that includes an "input" for plastic tips is JBM's, www.jbmballistics.com›cgi-bin jbmstab-5.1.cgi
