Just a thought.........Have you tried a powder in the rl23, 560 or 555 range? Or even RL17or H4350? All The throats improved in that fashion I have dealt with have produced as they should.
Ackley does a better job of hiding pressure. Who wants their face rubbed in “it” early when you know you’re going to go “too far” from the start? The improved case is an easy-ish way to kick the “too far” can down the road another hundred or two fps. Or at least that’s why I would do it.
Barrels are unique. Each and every one of them. I have had 3 different brands same chambering and same length running the same "load" range from 3400's to 3100's as dictated by pressure. I do load development all day everyday and see a lot of different stuff. I just had a 28 nosler that...