9MM AR Question?!?

dreher

I have an extra 5.56 AR lower and have thought an upper in 9MM could maybe be a lot of fun to play with. I'm guessing that this isn't as simple as getting a 9MM upper and just sticking the upper on my 5.56 lower. So what all do you need other new mags??

spirits

I've thought about the same thing "Wouldn't it be fun to have a 9mm AR Upper on a Spare Lower". Problems are 1) it is a blow-back and harder on the pins (steel pin in aluminum hole), 2) may require a heavier buffer and higher tension spring although the bolt may be designed to be heavier to alleviate replacing them, 3) maybe an un-notched hammer, 4) new magazine as you noted, and 5) probably something(s) I missed. The more I thought about this 9mm AR upper and considering I find myself more often walking around the hunting lease with the light M4 and running into big hogs I decided the 5.56X45mm would kill better (i.e., more accurate and kinetic energy). The only fun uppers I have are accurate tactical solutions 22LR dedicated uppers.

proapp

I used a hahn block in the mag well and modified cheap uzi mags(I think thats how hahn is spelled).

fordsix

you need drop in mag adaptor ,9mm upper ,a different buffer and with a bump stock mag dump in 1.3 sec = funnnnnnnn

dcs shooters

I had a Colt upper on a Bushmaster lower. It had filler blocks in the mag well. Fun to shoot, but Colt mags expensive and hard to fine.
Had four 9mm rifles them and sold two.
Kept the UZI and Beretta [;)]

fordsix

metal form magazines are the best and are available