If you take the bushing out of the die, you'll see it's beveled a little, so you can see it can't size the neck all th way to the shoulder, no matter how far down you screw the die in.
Then if you set the bushing to move or center a little bit, as per instructions, you get more the neck not being sized.
With the numbers you qouted, I don't think it's a problem with your gun. Going to .366, means with a seated bullet, it probably measures .368, or .369, so only .002" expansion, that's actually tight, a good deal. And your donut, if there, should really never cause a seating issue.
I have two 6.5x47's, loaded round measures .288", neck is reamed to .293", that's .005", you can see the difference.
If you need more info, pm me and I'll try help.