Hard pedal

it is very hard to move any caliper piston.By design the piston in the caliper will not slide through the o ring easily.The o ring grabs the piston,distorts or rolls allowing the piston to move about .005 to apply pressure to the pads.When the pedal is released the o ring returns to shape pulling the piston back.This takes very little brake fluid to push the pistons .005
..the pistons do not normally make contact with the caliper bores.