robinny said:
I have run it through the Gordon's Reloading Tool simulator, and was very surprised at how big the charge range was. Hodgdon says something in the neighborhood of 13.5 grains starting to 14.8 grains max IIRC, whereas GRT doesn't give a low pressure warning until you go down below 10 grains and high pressure above 15,
You have to keep in mind the simulators have limitations. The powder models are not exact and frequently are better at one end of the load range than at the other. I've used QuickLOAD for two decades and GRT since it became available, and both need confirming calibration. You have to remember they have no direct way to allow for primer differences or bullet jump to a throat, and they assume ideal barrels, which frequently means their velocities are a tad on the high side relative to the peak pressure calculated. What these programs are really good at is small relative comparisons. You change powder charge 2% then the relative change in pressure and velocity values are usually pretty close.
In the case of your load, using case water overflow capacity of 39.50 grains (QL default value; a little low IME, but I used it anyway), I had to increase GRT's Ba (powder burn rate factor) from 2.7118 to 3.3077 to get a peak pressure match to Hodgdon's measured data for 14.8 grains in their 8.275" test barrel. Velocity still fell short 26.1 fps. In Quickload I got to a matching peak pressure by changing the powder burn rate factor to 2.9825. It got closer on velocity, being down only 7 fps. Lowering the load to 13.5 grains, QuickLOAD was under pressure by 660 psi, but over velocity by 6 fps. In GRT, changing to 13.5 grains came up just 391 psi short on pressure and just 4.8 fps short on velocity.
So, of the two, the adjusted GRT simulation did better at the low end of the load range and QuickLOAD did better at the high end. But that's all after first forcing a pressure match to the data at the high load in Hodgdon's measurements. If I go with the powder defaults and that same 39.5 grains case water overflow capacity, GRT pressure is -22.4% low and its velocity is -79.3 fps low, and Quickload's pressure is -20.9% low and its velocity -75 fps low.
So, for accurate predictions, it is always best to a peak pressure match to measured data with interior ballistics software. IME, they have a harder time with straight wall cases like the 44 Mag than they do with bottleneck rifle cases, so it is most important with them. Generally speaking, bottleneck case numbers are closer to Hodgdon data even with the defaults, but I like to crosscheck them anyway whenever possible.
