Nice piece.
Have you thought any about what optics you are going to use. Lot of good stuff out there now. Seems like the war machine has lead to the development of some pretty neat stuff. Kind of like how we got Velcro from NASA.
Any problems with that 90 round mag. I was thinking about getting a few, due to the cheap price, but wasn't sure about function. It looks like having all the weight on the left side might cause, or contribute too, accuracy problems.
Have a good time,
Chris