Manuals reflect the conditions on the day of the test, using the exact components and firearm only. Even environmental differences(temperature, humidity, etc) on the day of the test matters. And it's entirely possible the data found in any manual, even the most recently published manual, was tested years and years ago.
"...vendors all use the same..." Nope. Hodgdon's site shows they used a 1 in 10 twist when 1 in 9.125 is "normal" for the .243.
"...brass vis-a-vis headspacing..." The brass has nothing to do with headspace.
The number of rounds loaded without a chronograph is probably in the billions if not more. How do you think we reloaded before they became cheap enough for anybody who wants one could?
QuickLOAD is not a manual. It's a computer program. Far too many variables that may or may not have been programmed into it.
"...vendors all use the same..." Nope. Hodgdon's site shows they used a 1 in 10 twist when 1 in 9.125 is "normal" for the .243.
"...brass vis-a-vis headspacing..." The brass has nothing to do with headspace.
The number of rounds loaded without a chronograph is probably in the billions if not more. How do you think we reloaded before they became cheap enough for anybody who wants one could?
QuickLOAD is not a manual. It's a computer program. Far too many variables that may or may not have been programmed into it.