denton
Member
If you're developing a software package like QuikLoad, you get to do quite a bit of math. You have to figure out the area under the pressure curve, with time on the X axis, for one thing. It's a challenge, which is probably why we don't have a lot of cheap, effective load modeling software in the market.
But if all you need is proportionality, the process is much simpler. Here is a scatterplot of data from my 8x57:
The relationship is obviously linear, and the math confirms that a straight line model accounts for 99% of the variation over the given range. Random error in the measurement systems probably accounts for the other 1%. I've done several of these, always with the same result. I suppose there are cases that aren't quite so neat.
So, if muzzle velocity is actually driven by the area under the pressure curve, how can muzzle velocity have a linear relationship with just peak pressure? Simple. The peak pressure is the main driver of area under the curve. Also, these measurements are taken over a finite range, small enough that any curvature in the model is likely to be small.
The big take-away is this: The bullet has no source of energy other than compressed gas, and the peak gas pressure is linearly correlated with muzzle velocity over a broad range. It follows that if you're exactly following a published recipe, and you're getting more muzzle velocity than the published load, you are also getting more peak pressure than the published load.
Unexpectedly high muzzle velocity comes from unexpectedly high pressure.
But if all you need is proportionality, the process is much simpler. Here is a scatterplot of data from my 8x57:
The relationship is obviously linear, and the math confirms that a straight line model accounts for 99% of the variation over the given range. Random error in the measurement systems probably accounts for the other 1%. I've done several of these, always with the same result. I suppose there are cases that aren't quite so neat.
So, if muzzle velocity is actually driven by the area under the pressure curve, how can muzzle velocity have a linear relationship with just peak pressure? Simple. The peak pressure is the main driver of area under the curve. Also, these measurements are taken over a finite range, small enough that any curvature in the model is likely to be small.
The big take-away is this: The bullet has no source of energy other than compressed gas, and the peak gas pressure is linearly correlated with muzzle velocity over a broad range. It follows that if you're exactly following a published recipe, and you're getting more muzzle velocity than the published load, you are also getting more peak pressure than the published load.
Unexpectedly high muzzle velocity comes from unexpectedly high pressure.
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