setter - because the formula for barrel pressures is not linear. You might have asked the same question this way. If they recommend 100 grains with 385gr conical, why don't they recommend twice as much for the 177 PRB which weighs half the amount? Because the weight of the projectile isof lesser importancein barrel pressure than is the raw powder charge. Doubling the weight of the projectile is nothing like doubling the powder charge. It might be possible to put enough powder in a barrel to blow it up with no projectile at all. Stick with the manufacturers recommendations for maximum charge and maximum projectile weight.

Good question. Keep them coming.