Yeah, it's called a BM59. Seriously though, back in the day some gunsmiths modified the Garand to take BAR mags. It was a rather involved process requiring much machine work. Not something one wants to try with a Dremel unless you have a lot of time and a crate of cutters. You might try a search on some of the Garand specific websites and forums out there, you might find somebody still doing it.