Building first AR pistol, seeking advice and input

[Notorious]

So after some rough estimation and playing with some parts at the gun shop, it appears that the AFG2 wouldn't work because it would end up sticking out in front of the barrel and even the gun store owner said it might melt.

The Ergo Grip is too borderline to call it and I would hate to run afoul of the NFA so that's out. Looks like I am going to have to use a mag well grip like CAA instead and go with that. Ugh!!!!