Reloder 28 is dead on about the full lenght resizing.
Head spacing on a break action is from the firing pin bushing to the rear of the shell casing.If the gun opens and closes properly unloaded then from what you describe the casing is not seating deep enough in the chamber.
You can take the barrel off the gun and drop in one of your reloads and see if it is proud of the rear face of the barrel.It doesn't take much to close the space.
The frame to barrel gap is not the head space.
