Ok I did the best I could without moving the rifle , because the model doesn't accept this in the game, so I had to play with the motion of both arms and shoulders to give the idea

this is a very short video sample : 7 mo you can see:
http://www.filecrunch.com/file/~cmkwdh

it's in avi ; just dl the little video on the disk and pay it with any player

let me know what you think