oneatatime wrote on Sep 1

^{st}, 2017 at 7:15pm:

uscra112, how about comparing the pressures at equal velocities rather than the velocities at equal pressures? The point for older rifles wasn't to get the most velocity at a pressure but to attain a black powder velocity at a lower pressure. For fun you might throw in 2400 and Unique also.

Well, the examples I cited all calculated to 1390 fps from a 24 inch barrel, give or take 10 fps or so. (Within the error budget of the model, I would think.)

You have a point, however. Powders

*much* too fast for a given application will produce higher peak pressure when loaded to a chosen velocity.

Unique, loaded in the model to 1390 fps, calculates to a bit over 21,000 psi. Red Dot is even worse. I want to guess that this is related to the total volume of gas evolved. The pressure curve for these powders falls off dramatically faster than the 4227 family. (If I remember my integral calculus right, the velocity would relate directly to the area under the curve, assuming you ignore friction losses.)

But 2400, again loaded to 1390 fps, calculates to 12,900 psi.

This is why I feel that the Government should be required to issue a copy of Quickload to every reloader at taxpayers' expense.!

I never look at paper manuals anymore. And since you can create your own cartridges, it's perfect for our old crocks for which loading manuals never even existed.

Funny thing, by the time I needed to use calculus for engineering problems, there were computers to do it for me. Later on I made extensive use of a function called the Fourier Transform, which I could not write a proof for to save my life, but no matter, just load the data into the software and push the button! I don't have a clue how Quickload's model works, either. But it does. It's never been far off when I get to the range. Usually a bit on the conservative side, so I wind up tweaking the load up, not down. It even made a fairly accurate velocity calculation for when I fired a double charge of AA#9 across the Chrony once upon a time.