Carey Farmer
Well-Known Member
In the pressure report image posted above, if I'm looking at this correctly, T4 projectile has 7% higher muzzle energy than T2, despite T2 impulse work (area under the pressure curve) being 35% greater than T4. I think that suggests there may errors in the pressure vs time measurements. Or perhaps in the muzzle velocity measurement.
I would also comment that for a given powder charge weight, "book" chamber pressures can be quite different for different bullet constructions. This is certainly the case with Hodgdon's reloading data center. And one sees that pretty clearly (via the typical pressure signs that handloaders watch for) when shooting Partition or Barnes bullets vs. Bergers.
Finally, even though very few of us measure our handload pressures directly, I have a relatively high level of confidence in the repeatability of ejector marks on soft-headed (Norma) brass as an indicator of pressure. And as I remarked earlier in this thread, my experience is that QuickLoad is pretty good at predicting what load will result in ejector marks (after tuning to measured muzzle velocity in lighter loads).
I would also comment that for a given powder charge weight, "book" chamber pressures can be quite different for different bullet constructions. This is certainly the case with Hodgdon's reloading data center. And one sees that pretty clearly (via the typical pressure signs that handloaders watch for) when shooting Partition or Barnes bullets vs. Bergers.
Finally, even though very few of us measure our handload pressures directly, I have a relatively high level of confidence in the repeatability of ejector marks on soft-headed (Norma) brass as an indicator of pressure. And as I remarked earlier in this thread, my experience is that QuickLoad is pretty good at predicting what load will result in ejector marks (after tuning to measured muzzle velocity in lighter loads).
