Found out what the problem was. @M1Garand is within another @M1Garand folder. It's packaged that way so when someone slaps it into their arma 3 folder it won't work. Testing out my sounds now.
---------- Post added at 04:26 ---------- Previous post was at 04:10 ----------
Size seems slightly off. Perhaps base the receiver more closely off of the EBR as the receiver sizes were quite similair, if not a little shorter (the EBR). Attached a pic to illustrate this. My edited sounds seem to be working well, I'll send them to you soon as I can.
http://i43.tinypic.com/anoio3.png (593 kB)
Another example comparing the EBR and M1, just to compare receivers, ignoring barrel length obviously.
http://i42.tinypic.com/34s2u55.png (612 kB)