Thanks, UncleNick, I rather suspected something like that was the case.
The limitations I see with the program are common to all programs, and that is GIGO. No program can use data it doesn't have, and literally, none of us who aren't equipped with a lab can test and measure the factors in our personal guns and ammo component combinations in order to enter them into a program.
That doesn't mean the program isn't useful, all it means it that its another tool (apparently a pretty good one) for predicting the most likely result of a given load. Again, a guideline.
My point is that one needs to understand that while other people's tested or calculated data is nearly always close enough to be useful guidelines, there is always the small possibility that our personal results could diverge from the usual, and though rare, could be enough different, in just the right way to actually be dangerous.
If you've done a bit of reloading for different guns, you've probably seen examples of the principle I'm talking about.
A certain load, listed in the books (or wherever) that shows primer flattening or cratering in gun A, but doesn't when the same ammo is fired in Gun B.
Same ammo, different guns, different combination of factors at work, (slightly) different results.
Another place its easily seen is the different velocities obtained firing the same ammo through different guns with the same barrel length.
We always say "start low, work up, carefully", because that is the safest method to determine if your gun/ammo combination is that "one in a million" where the stars line up the bad way.
I know it can feel frustrating, especially for new loaders, it seems like the bullets and powder spent with starting loads (or under) is just wasted. But really they aren't. They are the price of knowing for certain where you are starting is a safe place. "Win" the gun/ammo pressure lottery in the wrong way, and you could lose more than the cost of your "ticket".
I try not to have more to do with Mr Murphy than I have to but I recognize that he knows where I live. He knows where you live, too!