Colonel, Imagine your 20 something mistress walking around your vinyl laminate kitchen floor in 6" stiletto's. Now the navy pumps.
One will leave a mark you can't remove before your wife returns, and the other can leave unannounced.

He's saying chamber pressures have to be higher for the same ejecta in smaller bores.

Same ejecta (mistress), same breech face (floor) , different pressures (heel sizes) and different evidence of pressure (dents)

Out there doing it best I can.