We were asked to do something rather unusual recently. A client wanted an 8.5" barrelled 50BMG rifle. A CQB 50 cal to be precise.
Based on a DA50 upper, new but very short barrel and significant modification to the hand guard, this is what turned out.
I have it attached to 1 my own lower for show purposes.
Let me tell you test firing it was truly a "blast"!!