A receiver is going to cost you more than an entire ADL or SPS. Brownells sells them for $400 retail but are currently sold out. Then you still gotta buy the other parts that go with it... floor plate, mag box, mag spring and follower which is another $125.

You'd be much better off getting a discontinued ADL for $299 or a new SPS and selling the parts you don't want.

I don't understand it one bit but that's the way it is.