AR15/1919 hybrid thing

I've been messing around in CAD software and I recreated parts of a Browning 1919 and an AR15.  My idea is to create an unholy union between the two.  Basically it's a heavy-metal receiver shell that you can attach an AR15 upper to and it uses an AR FCG, but it handles like a Browning 1919, complete with spade grips and can be mounted onto an M2/M3 tripod or a standard vehicle mount.  There wouldn't be any real purpose for this, but I'd like to put a FM-9 9mm belt-fed upper on it, or a Fightlite Industries MCR.  Basically the fun of owning a Browning 1919 but with cheap ammo.

A flat-based AR receiver in progress.

Browning 1919-like receiver with an AR15 upper.

The extension below the bottom plate is a protective housing for the AR15 fire control group.  I could have just cut the finger off and avoided that unsightly extension, HOWEVER, I wanted to be able to use off-the-shelf FCG units such as the Fostech Echo Trigger without having to modify it.