Thread: 7 PRC Wild Data

Originally Posted by LJP

I have a decent stash of N570 that's gathering dust. I might be persuaded to part with.

LJP I've sent you a pm

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Greetings All,
First I need to be clear that the following is only an explanation of the observed data from this thread and not a recommendation of it's use or otherwise.
The relationship between velocity and pressure in a particular cartridge is quite linear and I often use this in trying to make sense of conflicting data of which there seems to be an inexhaustible supply. After reading the posts in the thread I fished out the relevant copies of NZ Hunter form the archive. An impressive list of articles from Greg as usual. The Hornady data is not specific to the 162 grain ELD-X but Hodgdons do provide specific data with pressures. Their max load was a little higher than the Hornady data and with slightly lower than max pressure. Next the calculator came out to give a theoretical max velocity at or a little below max pressure. Next the velocity was reduced to what would be reasonable for the 20 inch barrel. The result was 2,960 fps for the 162 grain projectile, the same as where Greg got to but he needed several more grains of powder to get there.
I briefly sat wondering what was going on until I remembered I had had exactly the same problem with the PSI data in my .223 which, in spite of a 26 inch barrel needed additional powder to match book velocities. The pressure barrels in use for PSI testing appear tighter than even min spec barrels. This was the case with the CUP test barrels years ago but as factory barrels improved the difference disappeared.
I am not advocating that anyone should exceed book data for that last erosive foot per second, just trying to explain how the differences mentioned in the thread may have occurred. It also reinforces my opinion that anybody working up a load needs to chronograph as they go, otherwise they are flying blind.
Regards Grandpamac.

Originally Posted by 25/08 IMP

LJP I've sent you a pm

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Sent you a PM with amount & pricing.

Originally Posted by 25/08 IMP

N570 looks good and about as expensive and hard to find as RL26

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1 kernel is about 1 grain worth of powder- from Viht themselves: "N570 is the slowest of our high-energy powders and is an extruded, tubular powder type with grain dimensions of 2,3 mm length and 1,3 mm diameter. Due to the large kernel size (similar to 24N41 and 20N29), we recommend you to always weigh your N570 charges rather than relying on throws from powder measures, as they do not always deliver consistent charges."

Would personally avoid this powder. Speed is not everything, better to have a slower but extremely consistent rifle vs. one which has 50-100fps velocity peaks and troughs!