" I would like to point out that it is unlikely that it was Moro armor which brought about the introduction of higher caliber hand guns in the U.S. military as very, very few Moros ever wore such armor. Only a handful of powerful datus would have owned such armor. It was the intense fierceness of the Moros themselves in battle that kept them coming in spite of having a few rounds of .38s in them. "
I was tooling around looking for stuff on this and stumbled upon this
http://newsgroups.derkeiler.com/Arch.../msg00999.html . I have read other sources regarding the poor penetrating power of the .38, but the Moro expiriences are something of a hallmark. The fella in the link above posits that the poor performance of the .38 during the campaign relates to the age of the loads, .38's had been in storage for a while, well the .45's for the revolvers brought in to replace the .38's were newly made shells, as the explanation for the poor performance of the .38. I cannot speak to the veracity of his claims but it certainly is an interesting theory and not something that would have occured to me.