MVB Industries .45ACP Pistol Kit for AR-15 Lower Receiver (Rainier Arms Exclusive) - $435.45

i got the pistol kit with the slightly more expensive pch-a buffer on sale for $190 last summer, no magwell adapter. it cycles well with 45acp on a 4' barrel

Or you could buy / build an entire lower for about half this.

Come on Rainier.... If you want people to plop down 400 bucks you can at least add that many characters to your description of the product and let someone know what they are getting and maybe what else they need...