I've also been extremely disappointed with the whidden dies. I've heard others,including my gunsmith comment about the quality of whiddens dies have recently gone through a change for the worse. The seating stem actually snapped at the top junction where it slides up/down in the die. That happened after 100 rounds being seated with constant seating depth issues. The necks had been sized& trimmed to .015 so it wasn't like I was forcing bullets into an undersized thick necked brass case to cause the stem to snap.
150' is a lot for sure, but that is the exception, not the rule. I had another experienced prs shooter run the 140's upto 3180 before he pressured out.I'm already at too high pressure at 54.4 w/ that coal,should dial it back to 54.0 w/ re 26. I can't imagine a bartlien barrel being that slower than others. I understand you mean that individual bbl is a "slow" bbl...but +150fps slow just seems quite excessive. I did mill out the raceway on that action& mag lips have been opened,feed ramp opened and polished but still some feeding issues.
I have a set from about two years ago that I am extremely disappointment with. The top of the seater (part that you turn) wiggles back and forth so much that seating depth changes considerably
I lot of folks really like the Whidden dies, and some don't! I am working on a deal with Forster to provide another option.
I think we are getting off topic from the O P's topic, but I would be happy to answer more questions on another thread......rich
P.s. Alpha type 4 mag seems to work very well.