Milling a 80% AR Lower for 9mm

[Lifeon2whls]

So I have a paperweight heading my way from Ares and I'd like to build a AR Pistol in 9mm. I've been researching the best ways of going about this but I've found some conflicting info and was wondering what opinions you guys had.

I'm contemplating milling out the paperweight as a traditional 5.56 lower and then get the appropriate parts (upper, mag block, etc) to fire 9mm. I haven't found a full "conversion" so I am assuming I will have to source each part needed. My only thought here is that it would be the least reliable way to go...again, just an assumption on my part.

The other way I am looking to go is milling out the lower to 9mm lower specs. I haven't been able to find much if any information about this and my biggest concern is finding a shop that is set up to do this. Another assumption on my part is that I can mill a standard 80% lower to accept 9mm mags, etc.

I had thought about milling to 5.56 and getting two uppers to shoot both calibers but if I am understanding the laws correctly, by having one of those uppers unused at any given time and the fact that I ALSO own a full size AR, this would constitute constructive possession (I also realize I SHOULD NOT order the upper until I have the lower finished with BB installed and sled).

Thanks for any help/advice.

[Lifeon2whls]

Bueller?

[newglockster]

Well, on the 80% lower, the magazine well is already milled out. So you can't just take out enough metal to have room for a 9mm mag. If that is what you were asking...

Idk anything else, so.... free bump!

[chillincody]

I would mill it out for 5.56 and just buy the mag and mag block etc you can have a pistol length upper in 9mm and 5.56 constuctive possesion only comes into play if you own a rifle lower and a pistol length upper WITHOUT OWNING A AR PISTOL LOWER if you have the pistol lower you can buy as many pistol length uppers as you would like the extra pistol uppers are just parts for your legal ar pistol

[chillincody]

Well, on the 80% lower, the magazine well is already milled out. So you can't just take out enough metal to have room for a 9mm mag. If that is what you were asking...

Idk anything else, so.... free bump!

I have seen a few 80% lowers with out the magwell drilled out it depends on the maker of the 80%
Tactical mach has no mag well 80%

http://www.tacticalmachining.com/80-single-shot-receiver.html

[10Rounder]

RRA magwell 9mm adaptor works really well. If u have an 80% will 556 magwell cut out already just use that. As far as the rest of the AR it cna be in 556. I would build it in 556 specs and mark it multical so u can swap between 9mm and 223/556.