Re: .223 vs 5.56 Chambers - HUGE bullet jump?
Sorry for the delay in getting back to you here. No surprise on the amounts you've cited here, as each rifle will have its own sweet spot; one reason not to put too much stock into the "accuracy loads" listed in the manuals. They serve as something of a guide as to what powders may be good starting points, but don't assume that the listed "accuracy load" will be the magic ticket. I've never really liked Varget for the 69, though it's great for the heavier bullets like the 77s and 80s. Still worth a try, and I'd expect to see decent results from this combination.
Loner's perfectly correct, too, about the charge weight. A tenth of a grain isn't a tenth of a grain, per se; it's a percentage of the total charge weight. It may be insignificant, or quite a bit depending on what that we're loading. Four tenths of a grain is an almost imperceptable difference in a 378 Weatherby. That same four tenths in a 22 Hornet can be an exciting educational experience that you, and your rifle, won't soon forget. Changes in the 223 need to be made in very small increments, lest things become exciting.
Other than that, sounds like the groups are coming around nicely, and you're seeing what the rifle is capable of!