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Old August 1, 2021, 05:52 PM   #10
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Join Date: December 26, 2004
Location: Idaho
Posts: 494
Originally Posted by Unclenick View Post
Just to be clear, a chronograph doesn't measure pressure. Matching velocity (actually, matching muzzle energy, but the two coincide) proves the average force due to pressure on the bullet over its whole trip down the barrel (less that needed to overcome friction) was the same, so average pressure was the same. But it doesn't tell you what the peak and muzzle pressure values that made up most of that average pressure were.

Nonetheless, as long as you are using the same charge of the same powder, it is unlikely the same average velocity would be produced if the peak wasn't averaging very close to the same value. There are some odd situations where it could happen, but they are mostly applicable to rifles shooting bullets too light for the burn rate of the powder used with them. I am just posting this detail so that someone reading the thread doesn't take the notion into their head that they can get peak pressure values directly from chronograph readings regardless of powder type. The relationship between peak pressure and velocity varies by powder, sometimes quite a bit.
To expand even more, there was zero evidence of anything associated with over/excessive pressures. No extractor marks…no flattened, cratered or pushed primers… case separation or splits. The rounds ran exactly the same as with standard primers. Winchester pistol primers even state on the box that they are for “standard or magnum” loads. How can that be???? Over 45 years of reloading I have had to adjust components based on availability with primers usually the issue. I have ZERO hesitation in using magnum primers in starting to mid range loads. Of course that is what “I” choose to do and absolutely NOT what I recommend anyone else to do. Anyone else should adjust their loads based on their own experience and judgement. I do not endorse using magnum primers, I just described what I choose to do.
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