assuming any printed load is safe is beyond stupid.
ANY component change from what was used as the initial test can skew the data.
There is a reason that books suggest starting low and working up....
You're absolutely right, as usual, and this situation was no different, on my end at least.
With my ARP barrel, I tried to work up to ARP's (constructor's) loads using the same components, except the brass was fireformed from new pieces. I got serious pressure signs (brass flow, loose primer pockets) at least 1 grain and 100 fps lower than ARP's loads with three different brands of brass from multiple lots. Despite following all the correct and suggested loading practices and more (including only neck sizing), brass would not survive with those loads unless it had been fired at least 4-5 times. Obviously powder and primer lots vary too, but I did try a bunch of different powders from multiple lots with no better results. As you can see, Constructor still says this is my fault, rather than admitting any issue with the barrel or loads.
When I sent this barrel back to him the first time for testing, he tested with "the same 50 pieces of brass he'd used for all 30 Herrett load development" per his own words.
My point in posting this is just to show that ARP stuff isn't necessarily "good to go" all the time, and good luck if you have issues because SOP seems to be "blame the customer". I think Constructor has done a good job of proving that again in this thread.
His 6.8 stuff might be fine, because the 6.8 is what he knows; just be cautious about anything outside the 6.8 with him.
