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Old December 8, 2012, 07:41 AM   #11
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Join Date: November 8, 2007
Posts: 2,001
If you change primers from standard to magnum, you will almost certainly increase PEAK pressure, although you may or may not see an increase in velocity.

So, you DEFINITELY need to reduce your powder charge and work-up again with the magnum primers.

That is a good idea even when just switching between brands of primers of the same strength, or even lots of primers of the SAME brand AND strength. There is a fair amount of data that showes that the different brands of primers can make really substantial differences in peak pressure. And those differences can be hard to predict, because they can change from powder-to-powder in a manner that depends on the cartridge the powder is used in. There is less data available to the handloader about the differences between different lot numbers of primers, but the people who test the powders and write the loading manuals have that data and tell us in the manuals to work-up a load again when just changing lot numbers of either powder or primers.

As for the value of changing to magnum primers for N-110, I doubt that it is helpful, unless perhaps for extremely cold weather. Of the manuals that I have which do vary primer types for different powders under the same bullet in the same cartridge, they do not use magnum primers for N-110. On the other hand, some manuals use the same strength primers for all powders with a particular bullet in a particular cartridge, so I can find N-110 data using both types of primers. You should use whichever type the data that YOU are using was developed with. (And, ideally, the same brand as the data, too, although that is just not practical to do for many handloaders due to availability issues.)

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