Interesting about the donut. I greatly prefer the 65gr Sierra anyway over the 63 SMP myself; accuracy seems just as good and the Sierra retains more velocity at distance, even at just 100 yards.
FYI with X-Terminator - it has always given me best accuracy at full maximum loads and likes to be run hot, but your loads are a little milder. You can probably find another accuracy node at higher velocity if you bump the charge weight up toward max. Check the Western Powders load guide (you can download it for free), they list loads with a lot of different bullets and have most of those you mentioned listed.
Also in comparison to CFE223 - XTerminator has always given me about equal velocity but with better accuracy. Something to be aware of with CFE223 is that it can be a fairly hot load with no pressure signs at all, until it's way too hot. XTerminator seems more linear in that regard and I've always liked it better, and it seems to be less temperature sensitive as well. It's one of my favorite 223 powders.
Hope that helps.
