Howdy All,

I have a lower receiver that's been sitting in my safe for over 10 years, so I think it's time to build this thing up.  After building the lower (just ordered a lower kit w/ Magpul Adj Stock from PSA), I'd like to get a 9mm upper.  I plan to use the Aimpoint COMP-ML from one of my 5.56 uppers on the 9mm, then get myself a suitable scope for that other rifle (my eyes are not what they used to be...).

Also, I will be getting a 9mm CAN sometime in the next few weeks to use on this upper and my Walther PPQ Navy.


Who do we like for 9mm uppers?

Any specific features to look for with regards to the 9mm caliber?

Thanks for any input.

CMOS

I really like my Foxtrot Mike side charger.

Because . . . .?


CMOS

After sandy hook I bought a complete 16" yankee hill upper kit with Hahn magwell adapter that used Colt mags.
Not sure who made the bolt.  Maybe cmmg.

I now have a Gibbs side charger with a cheap 8" bear creek barrel.
I use a mean arms mag adapter and the same cmmg bolt.
Runs perfect. never a malfunction.

The mean arms mag adapters work great.
Stern defense makes decent adapters for Glock mags, Sig p320 and others.
Hahn makes colt style.

If I had to buy complete and I had a strong budget I would buy a cmmg upper with their RDB system.

I built mine with an 8.3" BA barrel and a KAK flash can to get the boom out in front of the 10" handguard I wanted to use.  Faxon 9mm bolt and F/M 6.5 ounce buffer.  Endomag inserts in 30 round p-mags.  Runs like a sewing machine with any ammo and bullet profile.

Guys, can I use the same buffer in my lower that I use for 5.56?


CMOS

And, I see a lot of sub 16" uppers.  Shorter than 16 is SBR right?  Class III?

Schuul me please.


CMOS

Or build a "pistol".

Not with a standaard blowback 9mm.  But if you go with a radial delayed blowback you can.

CMMG RDB.

My CMMG delayed blowback upper is way better than my blowback side charger.

Call Rudy at macon armory.

Why? He makes the best 9mm uppers and they will feed spent brass.

Can you post a link to that specific upper?

CMOS

I will do that.

CMOS

I built using this… https://cmmg.com/barrel-and-bcg-kit-5-4140cm-sbn-9mm

Do you understand the differences between blowback and a delayed action in PCC’s/subguns?

Yes, like the old HK 9X series carbines and MBR's however, tell me about the context in which you are bringing this up?  Meaning, what does this mean to me with reagrds to planning this dedicated 9mm upper?

CMOS

Just make sure you’re comparing apples to apples.

Most 9mm pcc’s are blowback.

Delayed blowback will have a delayed locking time, keeping the bolt closed longer. It makes it smoother and suppresses better. (DB’s and blowback/gas to face.) MP5’s are roller delayed and a great example of this.

The CMMG RDB would also let you use the buffer you normally use instead of a longer heavier buffer that is just for your blowback 9mm upper.  (That inertia also is what makes them kick so much *for a 9*)

All those nuances are amplified more with a silencer or happy switch.

Boy do I have a lot to learn . . . .



CMOS

Honestly don’t over think it.

If you want complete, buy a CMMG RDB upper if you want delayed blowback. Buy a MaconArmory upper from Rudy if you want blowback.

So most the companies that sell 9mm uppers, let's say PSA, for in the upper $300 range are going to be blowback?

There's no specific mention of the blowback type so I guess, based on the price, that it's a regular blowback, not a DBB.  Correct?

These uppers also do not specify what type of buffer is required so things are still a bit muddy for me.

CMOS

@Donut777donut

Will a simple blowback design run with a 5.56 buffer?  Since this will be a dedicated 9mm upper I want to get the right buffer (before I start building the lower).  Big difference in cost between the CMMG upper and a basic blowback.

CMOS

No, 9mm blowback uppers require a longer and heavier buffer. (Blowback bolt is shorter, radial delayed uses a standard carrier.)

I use the Spikes ST-T2 powdered tungsten carbine buffer in mine.  It seemed to solve all the problems.

I have a 10.5" RRA that was cut and bolt ramped by Adco.  They actually sold me the upper.  I had a few issues at first and scrapped the Uzi mags. Metalforms run great.

Runs with or without the can.  115, 124, and 147 all flow smoothly.

This.

My SBR CMMG banshee with a obsidian 9 on it is stupid quiet and very low recoil if any.
And the whole " the springs go bad after 1000 rounds " stuff has not been my experience.
I use it for training and shoot house work and Im clocked at around 3500 rounds without a issue at all.

I'm leaning towards the CMMG.  What 9mm magazines and adapter are recommended?

CMOS

Yes. Do that.  Rudy is the man.

Topic Moved

I’ve been pleased with my https://karrisguns.com/9mmuppers

CMMG Banshee and a Dead Air Wolfman can

Use the CMMG Pmag inserts.  Uses a standard Pmag body, no magwell adapter required.

https://cmmg.com/magazine-9-ar-conversion-30rd

With respect to delayed blowback: the H & K (Mauser) and Thompson (Blish) configurations are in-line ramp systems; the CMMG configuration is a rotary ramp system; hydraulic buffers are in-line telescopic systems.  There are several other delay configurations that have been implemented for firearms use.  All provide delay to the initial recoil pulse.  All have their pros and cons.

The recoil energy and recoil pulse are quite different for 9mm and 5.56x45.  While there are some recoil spring and buffer configurations that can be used in connection with AR-15 pattern firearms for either caliber upper/lower configuration, a single use recoil spring and buffer configuration will have compromises for either or both calibers.

I was already heavy into Glock mags before the CMMG system was introduced.  The financial tipping point between using a magwell adapter plus Glock mags or using MEAN Endomags is generally calculated to be five.  So as well as the size and weight downsides to Endomags, they would be a total financial loser for me.

With those considerations in mind, I use a magwell adapter and Glock mags in connection with one type of hydraulic buffer and recoil spring for 9mm shooting using a ramped, direct blowback bolt/carrier group; and swap to a different type of hydraulic buffer and recoil spring for (D.I.) 5.56x45 shooting at the same time I swap uppers.

Best of luck with whatever you decide to pursue.

Disclaimer:  I have no affiliation with or financial interest in any vendor or manufacturer; and I am not a competitive shooter or a blogger who receives any form of compensation for endorsements or favorable public or private comments.  Use of vendor and/or product brand names, if any, is for informational purposes only; and products or services were purchased from regular commercial sources.

Best of luck.
MHO, YMMV, etc.  Be well.

You can also get from the source.
MEAN makes the 9mm inserts for CMMG:
https://www.meanarms.com/products/detail/endomag-9mm

I use them in windowed Pmags also just fine:
More info on my site:
https://c3junkie.com/?page_id=280

I really like my FTM traditional style.

Runs good suppressed or not.
Never Jams.
Seems accurate.
LRBHO works as it should.
Takes Glock or Magpul Glock Mags.
Looks good. Fit and Finish.
FTM seem to be a good company.

Can't imagine much better, unless maybe spending much more, even then not sure how its going to be better.
Already said, but the most important part, Runs good suppressed or not.

You don’t know what ya don’t know…

I guess thats ok...

Someone's always cooler, got more money, is a bigger dick, faster car, bigger truck, etc.. etc...

If it is accurate and runs good 100% of the time, at this point, I just can't see spending more $$$ just to say I did, or just because I can.

Second that.  Rudy is the man.  He tuned up my BA 9mm barrel and built a sweet upper for a friend of mine.  Top notch work, great price and super fast turnaround time.

Eta just buy a buffer from Rudy as well.  It solved a couple problems i had when using a shitty Armaspec srs or whatever that pos is called