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Old 06-03-2018, 09:04 AM
WR Moore WR Moore is offline
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First off, let's look at the pressures. The published pressures are Maximum Average Pressures, not to be exceeded. Ammo companies load their products to velocity/energy specs within acceptable pressures. They don't load every lot to max pressures. Speaking of which, since CIP & SAAMI locate their pressure sensors differently the same round will show different pressures in the different test fixtures.

About the energy specs, please note the phrase in the post above: "From a standard proof barrel". We don't know the length of that test barrel, we can expect that it's got much tighter tolerances than production service pistol barrels. All of which can jack up the velocities.

I expect most of the folks on this board aren't old enough to recall ammo catalogs from before chronographs were widely available. [Bear in mind that whoever develops a cartridge and standardizes it with SAAMI gets to establish all specs. Including length & dimensions of the test barrels.] Back in them thar days, published velocity specs were often optimistic to varying degrees.

Along came readily available, accurate consumer chronographs and people started screaming about the ammo not coming close to published velocities. This led to SAAMI deciding to make handgun test barrels the same lengths as generally used firearms in that caliber. Revolver test barrels got vents to simulate gas loss from the barrel cylinder gap. Published velocities dropped and became a whole lot more realistic.

Would be interesting to get significant sized samples from various manufacturers and running them through the same test guns/test barrels.

Last edited by WR Moore; 06-05-2018 at 05:15 PM.
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