If you go from 7/8 Ounce to 24 Grams, you will have converted to the Metric System of measurement. Then your pressures may be expressed in KiloPascals or Bar. Velocity will change to Meters per Second and you will also notice the Targets dimension will now be expressed in Millimeters. Screws everything up.
Realistically, a few less pellets, a touch less pressure, and a slight increase in velocity would be the expected result. What you actually get might not conform to the norm.