So for BRN-180 builders, if you choose a BRN-180 Lower, there are multiple options for your stock attachment. These include using an AR folding tube adapter or a Picatinny adapter to accommodate a SIG MCX folding stock, which, incidentally, derives its design from the original AR-180 system...
The action had to be shortened slightly to work with standard AR lowers, but it doesn’t appear anything was lost when doing so. The fit between the BRN-180 upper and any of thelowerswe tried was superior to the fit of the original AR-180s, which are, to put it nicely, rather slop...
Rather than trying to build a clone rifle or reproduction of the original AR-18/AR-180 Brownells decided to do something a bit different. It decided to build an upper receiver as it felt it would currently appear, and it is designed to fit onto a standard AR-15 lower receiver. ...