Just my opinion- there are more accurate predictors NOW about the relative effectiveness of a cartridge than Hatcher. HOWEVER- you did not ask that. Pull up the ballistics for the round you are looking at, and use this:
The original formula was:
RSP = MB * A * F
RSP = Relative Stopping Power Index
MB = Momentum of the bullet in pound feet - (WB/450240) * V
(If you know the kinetic energy and the velocity you can divide the KE by the velocity to get the momentum.)
A = Area of the bullet in in2
F = Form factor derived from the chart below.
Bullet Type "F" / Bullet Type "F"
Fully Jacketed Pointed .7 / Lead Flat Point (Large Flat) 1.1
Fully Jacketed Round Nose .9 / Jacketed Softpoint
(unexpanded) 1 - 1.1
Fully Jacketed Flat Point 1.05 / Jacketed Softpoint
Fully Jacketed Flat Point (Large flat) 1.1 - 1.2 / Lead Semi-wadcutter 1.25
Lead Round Nose 1 / Hollow Point (unexpanded) 1.1
Lead Flat Point 1.05 / Hollow Point (expanded) 1.35