Your attention M41A Pulse Rifle weapon model for Half-Life for by  Sacrecrow.
The difference between these archives:
http://hl.gamebanana.com/skins/131549 and http://hl.gamebanana.com/skins/124621
1. Containing two versions - gray and green.
2. Are correct authorship!!!
Make a backup of the original files before you can use it.