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Changing brands but using the same type of primer will also usually result in pressure changes, but ordinarily these will be less drastic. In the A-Square tests the pressure spread between the CCI 200 and the hottest standard primer (the WLR) was 9600 psi. The spread between the mildest magnum primer (the Rem. 9 1/2M) and the hottest magnum primer (WLRM) was 8300 psi. These are significant pressure variations that cannot safely be disregarded.