reloading for accuracy

[Robert1234]

That might work, but I might try a chronograph myself

Fixed it.

[milotrain]

Increased pressure doesn't equal more velocity.

Tell us more.

[RestrictedColt]

Ok, sure, whatever.

It's fact, like it or not. Many conditions can yield high pressures and low velocities.

There are times when an increase in powder causes a decrease in velocity and vise versa, something that many don't believe that I've confirmed to be true.

Similarly; a decrease in powder and increase in case capacity, like a shallow seated bullet, can cause a severe increase in pressure with a decrease in velocity. Go put together some light .44mag loads with H-110 and shoot them over a chronograph. Wear safety gear so you can hopefully report back with the velocities and how many you got through before the gun became scrap metal.

[RestrictedColt]

Interesting. Every time I have increased the OAL I had to increase the powder charge to match the velocity of the shorter round. Different physics must have been at work between your rounds and mine .

While your findings are very common, it's not always gonna work that way; you also don't know whether or not the pressures were increased or decreased.

[ar15barrels]

There are times when an increase in powder causes a decrease in velocity and vise versa, something that many don't believe that I've confirmed to be true.

Anomalies are obviously not the norm.
That's why we recognize them as anomalies.

The norm is that increasing pressure increases velocity.

[rsrocket1]

I ran these calculations a while ago and while it is only theoretical (Quickload and plotted with Excel), it does follow that an increased seating depth (shorter OAL) does increase both the peak pressure and the muzzle velocity. Unfortunately it increases the peak pressure faster than the muzzle velocity.



Another one of my graphs has been copied and is now all over the Internet, but just like the famous plunk test diagram, if it helps us reloaders understand what's happening, feel free to copy and distribute (just don't try to profit from it monetarily)

Anomalies occur typically at top end loads when powders start to behave erratically. When that happens you should back off and either settle for a lower charge or if your requirements dictate a faster MV, use a different powder.