Hmm, when I look a little closer, It looks like a regular M4 receiver, with Hk416 trades. I noticed that on a 416 receivers it shows almost like a slope shape, like there a "hill" starting. Look at the rear sight area, and it will almost look like theres a "hill" going up.
Ill give you a link to what I mean.
http://s272.photobucket.com/albums/j...Comparison.jpg
Its not the greatest picture help, But if you look at the "true" 416 receiver, and compare it to the M4, there will be a differnce. Also take a look at the hight in the longer red circles :
http://s272.photobucket.com/albums/j...omparison2.jpg
The M4 receiver sets almost looks like what the receiver set looks like on redwolf does. Dang its hard to find the true 416 receiver sets!
Hope that clears things up
