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Old 07-18-2019, 06:11 PM
Steve Newman

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Very interesting information, gentlemen. Wanted to add that, yes, while powder manufacturing does change/evolve with time, and today's IMR, Winchester, VV, Hodgdon may have a different formulation/burn rate than it did 10 or more years ago, it is still normally within a narrowly defined tolerance. And as noted, bullet bearing surface/shape differs among different manufacturers, even of the same weight. But what skews velocity variations even more, is that there is no industry standard testing methodology. Some manufacturers use a universal pressure testing receiver and 24" test barrels, while some use an off the shelf production rifle with as short as a 16" barrel, in the case of a .556 NATO chambered, AR style carbine. And not all test loads are tested to their officially rated SAMMI pressures; some are tested lower, some even higher. Agree you can't meaningfully compare different loads to each other, without publishing the CUP pressures along with the loads. The main reason I handload, is to have more consistent, shot to shot (and therefore more accurate) cartridges, than any factory can produce, specifically tailored/fitted to my individual rifles. With only a couple of exceptions; maximum pressure/velocity charges rarely give me the most accurate results in the calibers I reload for.

Last edited by Steve Newman; 07-18-2019 at 06:14 PM.
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