Papazip,
Something's fishy with the Lyman data. IMR4320 and IMR3031 have about the same energy content. IMR4320 is the slower burning of the two, yet the data is showing the 28 grains of IMR4320 giving more pressure and velocity than 28.5 grains of IMR3031. That's pretty much violating the laws of physics as near as I can tell.
QuickLOAD thinks the pressure number for 28 grains is about 8,000 psi too high, even though QL comes within 12 fps of the same MV just with its default settings. Hodgdon puts the starting load at 30 grains and the maximum load (170 grain Sierra Flat Point seated to 2.550 COL) at 32.5 grains. Both use Winchester cases, though Hodgdon uses only the WLR primer while Lyman used a CCI 200 primer instead for some of their tests (and don't say which ones), that shouldn't make that large a difference. That said, Hodgdon's data gives 30 grains and 32.5 grains 1976 fps and 2068 fps, respectively and a pressure difference as just 900 CUP. I have trouble believing that, too. Lyman's getting about 69 fps/grain of powder, and Hodgdon is getting about 37 fps/grain. Something's amis there that I can't account for.
But in any case, you have an example of a published 30 grain load that's working just fine.
I think part of what we are seeing here is an example of the notoriously squirrely nature of copper crushers, as that is what Lyman and Hodgdon are both relying on for their pressure data. Below is the result SAAMI published for one lot of .30 Carbine reference loads sent to 9 different test facilities for copper crusher tests. Note that the average pressures measured vary over 23%. A similar test (357 Magnum reference ammo this time) done with conformal Piezo transducers got agreement within just over 11%. So the old system just isn't very good on absolute accuracy and I think you're seeing that problem in the data from both Lyman and Hodgdon.
Do you know what velocities you are actually getting? Do you know how to watch for
pressure signs? If the former are within reason and the latter are not present, you are good to go.
