Half Life Model Viewer - No Muzzle Attachment Help!!!!

[overki11]

I have been putting skins from CSS into gmod, and I fix the world model correctly, and I edit the QC, recompile blah blah blah and then, when I go into Half Life Model Viewer to fix the "muzzle" attachment so that bullets actually look like they are coming out of the barrel... there is no muzzle attachment. How do i add one? or how do i fix this? I have been following this tutorial right here [url]https://www.youtube.com/watch?v=w6lQSt_v3rs[/url]