What upper for 9mm pistol build?

sigboi · Feb 2, 2017

Hey guys, been itching to build an ar pistol after trying out a friend's. More for fun, and maybe a nightstand/trunk gun. Palmetto has these three uppers in varying lengths, all at $399.

What do you guys think? I'm a little partial to the shorter ones as I like that compact look, but I'd like to hear your opinions!

Flopsweat · Feb 2, 2017

They all look pretty badass to me. The 7.5" gets you a noticeable increase in velocity over the 4", while the 10" doesn't get you a lot more than the 7.5". BBTI - Ballistics by the Inch :: 9mm Luger Results

Kruel J · Feb 2, 2017

I'd go 7.5" for sure. You will be able to get a better grip on the handguard.

2Wheels4Ever · Feb 2, 2017

I have not heard raving reviews on the psa 9mm. ATI came out with one that is supposed to be good. Ymmv

Member 3687 · Feb 3, 2017

I just completed mine and went with an 8.5 but my intention was a 7.5 but could not find a barrel at the time I wanted it.

My logic was if I wanted a short barrel then my Glock 17 all ready fits the bill and if I am going to a 10 inch or longer then I should just do a 5.56.

I built my upper with a standard AR upper, Faxon barrel and a Faxon 9 inch hand guard with a KAK flash can on the end.

I did a Frontier armory lower and they make them for PSA from what I understand but they are not the same design. See vid below.

Most of the problem with the PSA set up seems to be that they use a STD carbine buffer and spring in their kits and when folks change them out with the heaver 9mm parts most of the problems seem to go away.

I have heard that some have had tight mag wells as well.

I have never heard of issues with their complete uppers in doing my research.

Have fun with the project.

AR 9mm Glock Lowers

my completed project

sigboi · Feb 3, 2017

Thanks for all the feedback, I'm leaning more towards the 7.5 as well. Might try to find a shorter muzzle device as that KAK one sticks out a bit too far for my liking.

Member 3687 · Feb 3, 2017

They do make a shorter one. in both 1/2-36 and 1/2-28 thread depending on your barrel that is 1.75 long instead of 3.25 like the one I have. I may order the shorter the next time I need parts as I did debate on what way to go. Its a good excuse to build another one so I can compare with out changing it out.

Edit: remember that my barrel is 8.5 so it pushes the flash can out an inch further than your 7.5 would be.

KAK INDUSTRY MICRO 1/2-28