Could somebody help me. m16m203 skin

I found a nice skin pack for CS:S and wanted to turn one of the guns into a working gmod weapon. I am going to replace the model of a gun pack with the aug skin but I would like to change the skin’s model first. I would
like the aug skin’s scope and sights removed.

The pack including the model: http://www.gamebanana.com/skins/27162
M16 sight removed: http://weapons.technology.youngester.com/2011/06/m16-disassembled.html

I would rather have done it myself but so far my lack of modeling experience is resulting in keyboard shaped bruises on my face.

I just accidentally realized the model has the rail for the removed sight. I still have no idea how to remove the sight.