That's fantastic. There's a few powders that are not thought of necessarily as "typical" 25-06 powders that show promise. H1000, RL25, 7828SSC, to name a few, fill the case and get in the ballpark velocity wise at a slightly lesser pressure.
I haven't experimented a ton, but the Nosler #7 best load of 57gr. of RL19 was really good in my Rem 700 and the NBT 85gr. This is a max charge according to manual. I am not a very proficient marksman and this shot 1.12" @ 100 in a 1976 BDL.
COAL of 3.250
0.060 from the lands
At the same...
If the sabot is loading differently, then I would certainly be suspicious. Go back out on a calm day and shoot her one more time. I have found that sabot differences affect groups more than powder charge changes.