Starting to put things together and determine overall length. Here is the bolt in the upper:
The bolt face is about half an inch into the receiver, when the bolt is locked, so I need a 17" barrel beyond the end of the upper to be legal.


This leads to the obvious conclusion that this rifle will have to be a SBR, otherwise it will be too damned big to be at all 'handy'. That still leaves the question of suppressing it, but having a suppressor, and an SBR may not add much, other then a bigger check to the BATFE.
Finally here is the receiver with a mag installed. That's a converted AR-10 mag that will feed .45ACP.
The next step is a lower parts kit, a stock and a charging handle.
AE