Here you go, Piston area and force.

Here is refresher about force v pressure. Same force was applied to each coin, but the end-on coin penetrated further because it more force per area.
Two pistons 4" & 5" diam, 1000 lbs in the chamber. Both pistons have 1000lbs of force applied.
The 4" piston has a pressure loading of 79.6 lb/ sq in; the 5" piston has 51 lb/sq in of loading.
The 'other' theory would be creating energy...where none existed to be created.