Step 4: Increasing Spring Power, Reassembly
Now, remember those two pennies and that felt pad? Grab 'em. Stick one of the pennies to the felt pad, and put the pennies (felt towards the back) in the back of the gun, where the spring used to reside.
Now, cut/shave down the cross on the back of the plunger assembly. It doesn't have to be neat, it just needs to be cut down, and the top of the cross should be even. (Pic 2)
Once that's complete, put the plunger assembly and spring back into the gun. (Pic 3)