Arms look a little short, but overall I like it.
Yeah, teh shadows are a bit buggy, but not a problem. The real issue is the white bg. It pulls the attention too much Id say. Well done anyway!
The shadow and the shading don't quite match up, but it's not too big an issue.
Apart from short arms and the rifle being a bit too tiny this is a nice picture. It also deserves a proper background.