That's actually an HBI intended for a Stribog that I modified to fit, so it has the detents for open and flat, but no default tension to either position.

I haven’t seen many reviews of this upper so far - has anyone here bought one and have comments after a couple of rounds fired? Thinking of snagging one and a folding stock soon.

I have a matador arms mat 9 to review.

I have a Brn 9 upper and BRN-180M BILLET LOWER RECEIVER enroute.  
I’ll be using Endomags as well.

I’ll update soon after assembly and range time.

I bought one. Impressions so far:

-It was initially tolerance-stacked with my KE-9 lower, I had to gently smooth out and remove some finish on the rear takedown pin hole on the upper. It’s a tight fit now. (The KE-9 upper I had on previously simply has a larger rear takedown pin hole. I was able to solve this without busting out a Dremel but may continue to smooth it out.)
-Charging handle takes more effort than I expected - not a lot of leverage - but isn’t so bad, especially if you pull with the charging hand and push with the hand holding the gun. Some sort of folding handle which increases leverage would be a nice upgrade.
-Front heavy, which is to be expected. Having a vertical grip on the gun - which you really want anyway for safety and recoil control - largely mitigates this.
-Disassembly is pretty easy except for having to slide up/down a piece with a non-marring tool. Brownells recommends using a ballpoint pen for that; I snapped the nose off one trying to do that

Now the positives:
-This thing is *tiny*. Fits in my backpack even without a folder (I plan on getting one anyway)
-It will cycle hollow points - the feed cone is huge.
-Glock mags seated with no issues. Dry fired it with no issues.
-The upper is monolithic and taller than most AR uppers so a lower 1/3 height optic sits higher, roughly around 2” to my uncalibrated face. I like this for NV compatibility and heads up shooting.
-The working parts in the upper feel “tight” which seems to indicate quality (and hopefully not tolerance stacking!) It’s also probably because I haven’t cleaned off the factory grease and lubricated it, much less fired it.

She’s a pig, but a likeable pig. Videos sometime later.

She’s currently outfitted with a BCM Mod 3 VFG, Magpul BUIS, and an Aimpoint H-1. This is in addition to the excellent SLT-1 trigger and Magpul grip/stock on the lower.
Future upgrades include a 9mm flash hider, Law folder (or other folding stock) and Streamlight TLR VIR-II.

Brn 9 assembled.

Shot roughly 200 rds…. mix of 124 gr, 147gr, Hush ammo, and FREEDOM X-DEF DEFENSE 9MM LUGER 147GR HOLLOW POINT (HP) NEW +P.

No malfunctions.
I used 4 different Endo mags but never got LRBHO though.

I will be going back to shoot next week with an Omega 9K and put the same ammo through the BrN-9.

I can confirm that the following lowers do not work:

Spike Colt-Style
Black Creek Precision Colt-Style
PSA Colt-Style

Are there any non-Glock/Sig dedicated 9mm lowers that we know work with no modifications?

Welcome to ARFCOM.

I'm not sure what you have going on, but I've built multiple BRN-9s on Spikes and PSA Colt lowers. Are you adjusting your ejector to clear the bolt?

Personally confirmed by me to work without modification on multiple BRN/MAT9 uppers:

All NFA lowers - Including CZ and MP5
Noveske Colt
Spikes Colt
PSA Colt

lol, thanks!  I joined years ago but wasn't active.  Couldn't find my login so had register again. :/



Don't know what to tell you.  For both the Spikes and BCP lowers it wasn't the ejector but the feed ramp that was the issue.  Range had a PSA lower they quickly test fitted it on and the bolt wasn't fully closing during manual manipulation on that either.  

Noveske lower is a bit pricey.  I wish NFA still made the S-9 Scorpion lower but it was discontinued for 2023.

Shot another round of similiar ammo through an Omega 9K with tri lug adapter.  

No problems.

LRBHO does NOT work however.

Have a new buffer we can send you that's completely revised. Let's the bolt travel further back and give the LRBHO time to engage.

Shoot me a PM

Sent.

Got her zeroed! Observations:
-Recoil impulse is not too bad; definitely a blowback but it’s not harsh by any means.
-Hats off to whoever designed the feed cone - it digested 15 147gr JHP (Federal HST) flawlessly. In fact it printed an 1” group at 25 yards with that ammo. Nice.
-“COVID ammo” is a real problem. Some 2020 production Sarsilmaz (Turkish) stuff had 3 cases of dimpled primer. It did not happen with Blazer Brass and has also happened in my Glock so for now the most likely culprit is ammo and not the gun. It’s also not particularly accurate - couldn’t do better than about a fist size 5 shot group with some odd fliers.

Looking forward to shooting a match with the thing!

You are too kind ;-)

That actually took a few iterations. Glad you're having a great experience with it!

@Axlnut How's that AR-V lower compatibility coming? Have you been able to make any progress getting it to function properly? I'm looking forward to your write up!

When you say you are using this with EndoMags, are you using the "regular" ones that have the ejector built into them?  Is the built in ejector needed with this upper/bolt design?

So I kept having problems with the Endomag extractors getting compressed and wrecked.

I wanted better reliability.

Installed Mat Arms MagX https://matadorarms.com/product/matador-arms-mag-x/and shot over 200 rds suppressed(Omega 9K)/unsuppressed.
Used 115g,124g,147g, 147gHP+P and Hush ammo.

Using  BRAND NEW PMAG 27 GL9 GLOCK magazine.

No problems except for HP .......on the last round only.  
The bullet was shoved into the casing and would not go into battery.

I'm chalking this up to brand new springs and will report back after more HP rounds shot down range.

 Ejectors?

10-4

Correct.

PW9 seems like a nice option.

That said, there isn't a single aspect of the BRN or MAT9 that is in any way a clone, copy, or even influenced by the PW-9.

I had never even seen one before initial production started.

Got it running well - one aspect of the machining needed on the bolt is a bit much for the DIY'er, and there's no going back from it (feed lug height change) so what I'm trying to do (amongst all our other product dev) is create either a very limited SKU for that bolt, or set up with a partner shop to offer the service.

It's such a niche combo/product that I haven't been able to make it a front-line priority, and for that I am sorry - hopefully soon.

Thank you.

So I believe I may be the first person to do a video review of the BRN-9. I only have about 300 rounds through it so this is more of an initial impression, and the gun is not yet in the final configuration I want, but after zeroing and function checking I took it to a match and was able to shoot it on the clock in a pretty dynamic environment, making rapid hits from 5 to 175 yards (!!).

While people keep trying to make their roller-locked AR-9s work (or are just awaiting parts!) this thing chugged along happily except when I tried to feed it COVID ammo.

Swapped out lower for FM9 glock style.  Shot another 150+ rds suppressed/unsuppressed ……no problems.

I suspect the brand new Magpul magazine springs were the FTF culprit.

LRBHO works flawless.

Very happy with ar9 now!

PSA Colt mag lowers use feed ramps that are shimmed up and may not fit….anything. I had to hand fit mine. Someone else posted about this at some point, also.

My guess is they drilled the pin hole in the wrong position and instead of tossing the parts they said “hey Bubba, do you think we can just shim it?”. Or there is something unusual about their uppers that required a taller feed ramp on the lower.