Were to get the xm8 weapon on mgs4?

in act 2 when you meet drebin. at the power station. just after the cut scene quickly put on the solid eye in night vision if you like. on your left you'll notice some rebels. follow them keeping the solid eye on.follow then around a cornor and you'll see a wooden shelter. it is in there. (by XM8 you mean the gun johnny uses i hope) johnny uses XM8 compact, Ed and Johnnathan use XM8