Is the nut on the slipper clutch tight enough? As the engine get's hotter, the clearances increase. I've had this happen before. Tighten the all the way down and back it out 1/4 turn. If that doesn't help, there my be something worn in the tranny. May be time for a rebuild.
I think backing the slipper nut off 1/4 turn is most times too much, I run mine almost cranked down tight, gives a better lockup between the engine and trans.....
I think the manufactures err on the side of caution when they design their products. Slipper clutches were great on motorcycles. Not sure if they earn their worth on a Savage!
Thanks guys it was the slipper clutch. I was backing it off half turn like I read. Tighten it down and backed off a 1/4 turn and bingo it shifts the same every time now. Thanks again Jeff