In canon he used the murder of his muggle father to make the Gaunt ring (which is inset with the Resurrection Stone) a horcrux, the murder of a muggel tramp to make Slytherin’s locket into a horcrux, and the murder of an Albanian peasant to make Ravenclaw’s diadem a horcrux.
But you’re right, this makes it seem unlikely that a Muggle victim would work. (Damn, these small differences between canon and HPMoR can really confuse me …)
On the other hand, it seems possible to use up a part of one’s magic/life force to create a witch or wizard (cf. Hermione), which could then be killed to create a horcrux. So while these horcruxes aren’t free to make, at least they are not a zero-sum game, either.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 112.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: