Eh for a little more you can get a cmmg - R&D Precision Pw9R Bufferless 9mm Upper Kit Complete

I got this trying to be cheap and have a 16" and use endo mags to keep the manual arms as close to an AR15 for cheaper ammo at the range. Well the endo mags do not work with this upper. I've tried a stiffer spring (for suppressor use) that R&D sold to me for another $45 shipped however that didn't work. I'm not knocking stars because of this. As far as I can tell, it'll work just fine with a pistol mag insert or a dedicated ar9 lower

What I'm knocking stars for is the design of this upper. First off I'm not a fan of how they designed the bufferless system. The spring is not retained in the upper. Because of this you have to slide the upper forward then slightly tilt it to remove the upper from the lower. The bufferless adapter is kinda large compared to other companies that utilizes bufferless lowers and is not aesthetically pleasing.
Additionally, it doesn't state it on this site but it recommends you use 115gr only and not to suppress it. Now you can get the upgraded spring for suppressor use but I didn't ask if it would allow for larger grain 9mm.
Lastly, the charging handle doesn't have a spring in it. So you need to push it back if you lock your bolt to the rear or the charging handle will slam forward and depending on your hand placement on the handguard and using ambi bolt release, it can hit your hand.