Here's an article on primer ranking according to their "spark."
Primers affect the pressure generated by the cartridge. Changing from standard to magnum primers may substantially raise the maximum average pressure of the cartridge and indiscriminate changes are not recommended. The A-Square Company conducted pressure tests involving six different primers. These tests used the 7mm Remington Magnum cartridge with a 160 grain Sierra BT bullet and 66.0 grains of H4831 powder and the results were reported in the A-Square reloading manual Any Shot You Want. A-Square used CCI 200 and 250, Federal 215, Remington 9 1/2M, and Winchester WLRM and WLR primers in these tests. They revealed a total spread in pressure of 12,800 psi from the mildest standard (the CCI 200) to the hottest magnum (WLRM) primer tested.
Article:
http://www.chuckhawks.com/primers.htm
Hope it's the one your looking for.
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