Don't be silly.
Did the first bullet/sabot powder combination you ever tried with T7 in that rifle shoot MOA? If it did, you're luckier than I have ever been.
Ya gotta give em what they like. They're like kids.
Not at all that surprising it is different with this powder. This powder is different from every other BP sub that has come before it in just about every way. Well, outside of the fact that it creates smoke.
My 50 cal Elite shoots 250 gr Expanders sub MOA with 100gr T7. 100 gr of BH209 more than doubled the group size.
I will abandon the bullet or sabot before I abandon the powder. It may be something as simple as inc/dec the charge. It takes time. Ya just gotta play with it. I haven't revisited the 50 bc I'm having too much fun with my 45s.
To get to a point that I am happy with accuracy out of the BH209 took me half a dozen trips to the range, two different bullets, 3 different bullet weigts, two different sabots, and three different charge weights.
This is similar to what I have seen it take to work up a smokeless load.