Ar pistol question

[USMC87]

I am looking at buying an AR pistol in 9mm luger and was wandering if I can buy uppers of say 10 mm, 40 s&w and 45 acp to use on the same lower receiver? Do the uppers have to be the same brand as the lower? I am looking at a pistol that uses Glock style mags by the way, I really appreciate you guys helping me.

[nagantguy]

Semper Fi brother; from everything by every brand I know after having played with the 9mm platform extensively is there isn’t the caliber compatibility, there just isn’t enough room in 9mm to go any bigger , and even in 10 mm you still just have a 10 mm lower, at least with the makers and platforms I’m familiar with. Picked an “interesting “ time to build , as in limited stock and ammo being magic beans but if you do your going to enjoy it. Not one single person has ever fired my 9mm ARs and didn’t have a huge smile or said “that thing sucks” .
The above is limited to mostly glock magazine platforms there may be adaptors or some other such wiz bang to mag a standard lower multi caliber capable but not to my knowledge with running Glock sticks.

[beshears]

ATF is looking at changing the rules on AR pistols using a brace. May require registering as a short barrel rifle same as a full auto. NFA classfication.

[bdicki]

Look here.
https://www.ar15.com/forums/AR-15/AR-Pistols/122/

[Ickisrulz]

Stern Defense makes an adapter that can take S&W MP magazines so one adapter can be used with 9mm or 40 S&W magazines. You'd just need to get two uppers. The use of an adapter frees up the lower to be used with 5.56 based rounds when needed (most likely a buffer change would be required).

https://getstern.com/mag-admp9-40-p320/

[USMC87]

I appreciate the help guys.

[Baltimoreed]

I went the other way years ago with dedicated .45 acp greasegun mag lowers and multiple uppers, a rifle, sbr and pistol. Don't have a .40 or a 9mm. I would agree that it’s a bad time to start on an AR pistol project. Been waiting for a cmmg rotary bcg and .45 bbl for a couple of months myself. Good luck.

[monadnock#5]

I put in an order for a CMMG-Banshee 200, .40S&W on Aug. 28. It's still on hold. Your project is one for which you'll need the patience of Job.

[Lloyd Smale]

you can go to a 40 with a 9mm lower that takes glock mags but the mags are different for 45s and 10s so they wont work. Pistol cal ars a are blow back not gas operated and id dont know if id want to play with a higher pressure 10mm in one. 45s are no problem though but you will need a differnt lower

[Lloyd Smale]

I put in an order for a CMMG-Banshee 200, .40S&W on Aug. 28. It's still on hold. Your project is one for which you'll need the patience of Job.

Im jealous. Thats about the Cadillac of ar pistol cal guns. Mine is just a 4.5 inch palmetto gun i put together. Ive got a cmmg 16 inch ar in 9mm that i bought about 15 years ago. That gun runs like a glock. NEVER misses a beat but takes the colt pattern mags. If you banshee runs like that one your a lucky man. Id love a take down banshee with a binary trigger but i just dont have 1500 plus for a gun these days. Nice thing about the cmmg is they have an actual feed ramp vs a tapered throat like most. My psa gun was a challenge to get running with many bullets but i found a drop in (well you have to inlet it a bit) ramp that made all the differnce in the world in my gun.

[1006]

These guys might have something, although not an AR. Check out the CONVERSION section.

https://www.tnwfirearms.com/default.asp

[USMC87]

I appreciate the links and the Aero pistols are awesome!

[SeabeeMan]

I'd also suggest you look at EndoMags. These convert a standard mag in a standard lower to shoot 9mm from the appropriate upper. They work amazingly well.