User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-216.63.243.212-20120901202347/@comment-5633664-20120902073804

I think it's just one to another.

Basically, Hammer can become Hunting Horn, but not the other way arounnd.

Thus, Lance -> Gunlance

GS -> LS

Etc,