T. O'Hier sometimes makes blanket assertions about things without doing his homework. His assertion about bullet weight being the only factor in load development is out of date. Former Speer employee
Allan Jones explains why in this article. He is also off the mark suggesting QuickLOAD was authored by people who've never seen a gun. QuickLOAD has just one author, Hartmut Broemel, who is a highly respected European ballistics authority who writes software for the CIP, among others, and who developed the basic program while working on government 20 mm gun studies. This was in the late 1960's, and as computer technology changed, he updated and circulated a basic version of it among industry insiders exclusively. This went on for a couple of decades before, at the encouragement of those same insiders, he wrote the published version. Dr. Ken Oehler said at the 24 hr Campfire, that Broemel had probably seen more real pressure data than anyone else.
All that said, the warning T. O'Hier copied from Accurate Shooter is the one thing in his post that is completely right. This is for two reasons: First is that the QuickLOAD model uses powder data derived from vivacity bomb testing of purchased samples. Just like load manual authors, unless you work for the powder company itself, you have no way to know whether a particular pound of powder you bought is on the high or low end of the burn rate tolerance range, so you always have the difference between QuickLOAD's test lot and the powder company's lot and your lot to consider. Click on the icon for a table with the + - at the bottom. Scroll down the result to see burn rate variation effects of pressure and velocity.
Second, QuickLOAD has a large number of arguments that may be individually tweaked for each load. It is very easy for an incomplete set of adjustments to these arguments to bring about a wrong result. For example, to err on the side of caution, the cartridge cases in QuickLOAD's database are mostly on the small side of actual case capacity and the chamber dimensions assume minimum headspace. For example, if you load the .223 Remington files, you see a case capacity of 28 grains. There is only one case I've ever seen measure that small. The average is more like 30.5 grains. Or .308 shows 56 grains capacity. Hodgdon develops its data with Winchester .308 brass which has closer to 59 grains water capacity. So if you use those default capacities in the program for those cartridges, results will tend to be high. Indeed, you want to measure the water capacity of your fired cases to get the most accurate reflection of pressure in your own gun.
Provide a specific example, and perhaps we can ferret out the cause of the error.
