Jason sent this link along to me yesterday, which shows another AR-15 lower design that someone came up with. Looks pretty simple, and definitely wouldn’t take all that much machining. The only thing that concerns me about deviating seriously from the standard AR design is whether an argument could be made it’s readily convertible to an M16 receiver. I believe AR-15 lowers have some extra metal in them to prevent insertion of a drop-in auto sear (DIAS). They also have the advantage of having been reviewed by ATF. I’ve heard ATF frowns on designs where conversion is just a matter of drilling a new hole. But I also believe (correct me if I’m wrong) that once you drill the holes for the AR-15 trigger group, being that they’re differently sized pins, it essentially won’t hold an M16 trigger group anymore, so that really no modern AR design can really be construed to be readily convertible. I’m wondering whether there should be any concern about a design that hasn’t been submitted to ATF in order to make a determination. Any comments?
I should also note that this is only a concern for people, like you and me, who don’t want to break the law. Criminals wouldn’t have any such compunction.