O.M., you are right that the little ridge is a carryover from the muzzleloader days. I do not know of any practical purpose for them so they were most likely something that was just carried over by tradition. Certainly the highly carved snails surrounding strikers grew out of muzzleloaders where they served to deflect shrapnel from an exploding cap. Tradition and attractiveness carried the snail through the entire era of hammer breechloaders.

John McCain is my war hero.