The general rule-of-thumb for single-based powders is that velocity increases at half the rate of the in pressure. This means around 100 fps in a load that gets around 2500 fps at 65,000 PSI. It's also about much velocity as a typical 286-grain 9.3 spitzer loses in the first 50 yards.
With double-based powders the increase is a little more, but not a vast amount.
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