The G3 magazine can be made to work. I had an M77 magazine but gave it to a friend. It's not much different from M-14 and Galil magazines. Spacing between the bolt and the magazine is an issue with the FAL magazine. More work than it's worth. I'd rather thin G3 magazines. The rim diameter is the same for 308, 300 Savage and 30-06. It's 308 that the rim is suppose be very slightly thicker. You can see this on the cartridge drawings and the military specs. Some companies don't make a difference and it's very small. I don't think rim thickness will be a factor but just something to note when fitting parts.