I can’t in a million years think that ATRS would make a product to fit a bcl lower. Yuk!
While I can see everyone’s idea behind this thought process, ATRS has a lower already designed for this product, and a stag 10 or bcl, or modern sporter, or any other receiver brings nothing to the table.
The lower they produce is much stronger than a basic AR lower, and makes a lot more sense.
I may actually be interested in one of these lowers even though I already have a proper 50