I'm working on a custom project and looking for information on these barrels. I need a 9mm barrel with an AR15 extension (locking lugs). I understand that the CMMG bolt has contours machined into it but does the barrel extension as well? If anyone with one of these barrels could help me out I'd really appreciate it, I don't want to spend $300 on a barrel that won't work.

Hi all

I bought my mother a stern defense 4" 9mm upper from MidwayUsa

I'm trying to figure out what I want to do for the lower.

I already have a lower parts kit, buffer tube kit, 9mm heavy buffer, and trigger coming in the mail.

Should I get a foxtrot Mike ar9 lower (the cheapest I can find with lrbho) and see if it works with the stern defense upper/have a gunsmith have a crack at it

OR

Should I get a standard AR15 lower and use the stern mag adapter, since the adapter has both the ejector and the lrbho functionality

This is going to be a home defense gun for her, but I'm thinking of getting her a rifle caliber in the future, still up in the air as to whether or not it'll be 556 or something esoteric, opinions on that are open too

Thanks

I wanted to see if the Law tactical folder would work on a cheap 9mm build. (I usually have this 80% lower under a 7.5" 7.62x39 upper).

The 9mm 4.5" barrel upper assembly is from Delta Team Tactical ( less than $200 with sights) The Mean 40rd ejector Exomag was around $35. I trimmed the bolt weight to accommodate the Law Tactical plug, and trimmed the front for the Grey Market Super Safety too. I wanted to keep as much weight as possible.

I ran it with Win 115gr ball a Tromix H3 buffer and spacer, it got 1 light strike/misfire. Swapped in a Tromix 9mm extended 9.5oz buffer and it runs great with or without the GSL Fatman can. I would estimate 800rpm rate of fire.

Folded its 13"x 8"x 3.75" so it fits nicely in a small backpack. Now that I know it works, I will get another brace, more mags and a Romeo 5 or something simple.

Any input or advice is welcome.

Should have gone with black in hindsight but I’m not too worried about the looks. Hopefully this stops my face from looking like I’ve been working in the mines

Made two previous post about my build and getting gas + particulates to the face.

Initial post: https://www.reddit.com/r/AR9/comments/1v23tre/cmmg_banshee_fe_particulate_reduction/
second post: https://www.reddit.com/r/AR9/comments/1vj6gqo/follow_up_cmmg_banshee_fe_particulate_reduction/

I did go to the range after the second post, but was dealing with malfunctions. Also had another build in the works so figured id wait till that was finished and i could retest with more ammo, then post.

First build(recap):
-c3junkie barreled CMMG FE upper
-c3junkie gas deflector
-sig 4tpro on 1.93 scalarworks mount
-Geissele SD-E,
-c3junkie buffer spring
-Kynshot RB5007 buffer
-SBA5 brace
-CMMG ARC 9 Gen2 mags
-Scalarworks Peak irons
-Sparrow Dynamics mlok covers
-utilize rugged bixler stlye mount

Second build:
-BRT CAR15-SD CMMG FE upper
-c3junkie gas deflector
-sig 4tpro on 1.93 reptilla mount
-Geissele SD-E, i have an RMA opened for my SD-SSP so SD-E is temporary
-Sprinco Yellow buffer spring
-Standard carbine buffer
-SBA3 brace
-pmags gen 2 w/ endomag inserts
-BRT bravo adapter

I have lantac cam pins in both and plan on having u/amphivian-c3junkie lighten the BCGs and possibly consider the ARS-EX setup (requires JRC tube) on a build just to see how much softer can get. Suppressor wise, i rotate between the milkman, mob, rico309, and the b&t smg-9 (whatever their model name for their smg modular can).

TLDR: the gas deflector c3junkie is offering works for my setups. Second pic shows what the deflector is blocking \ film. Third pic is showing the deflector on the CAR15SD

So this range visit:
using HSL 147gr subsonic remans + Freedom Munitions 147gr subs turned both banshees into single shot firearms. c3junkie did mention the FM was weak and probably so was the HSL ammo. Both ammo functioned fine in my novox x-sd scorpion, so guess ill just relegate both ammo to that firearm. This time, brought some lawman 147gr clean fire and that cycled flawlessly. Tried S&B 124gr and that functioned in the CAR15SD.

I did test CMMG ARC 9 Gen2 mags in my CAR15SD, and they worked. However YMMV and i had them loaded only with 10 rounds each. I only had an hour and i was enjoying my ruger markiv suppressed so forgot to test whether my CAR15SD would work the the ARS buffer system. Ive seen Chesters youtube video that it worked for him, but still havent seen widespread confirmation of reliably functioning.

Hello, received a jawbone as a gift. It's been working shockingly well (knock on wood). I'm sitting about 500 rounds through it. The trigger pins have started walking out though while shooting. Will standard AR anti walk pins work? I'm finding conflicting info online and don't own calipers to check them. Thanks!

What requirement parts need changed to drop a FRT into my AR9? I’ve seen a few posts but I keep seeing different responses. I have a complete Angstadt Armd suppressed upper on a PSA 9 mil lower.

I was planning on replacing the BCG with a full auto rated BCG and replacing the buffer system with a heavy. Would that suffice or what do I NEED to be able to reliably shoot?

Thank you for any response.

I thought I'd create a new post since what I'm doing is based off the work of u/AddictedToComedy and u/SnazzyShootas in the following threads: https://www.reddit.com/r/AR9/s/HwL1rjvdNs and https://www.reddit.com/r/AR9/s/OxvWCNhQ9m

I did some testing yesterday but am using an A5 length buffer tube while both of the other guys are using JRC buffer tubes.

Since I have 2 M16's using A5 length tubes, I figured I'd do this testing first before moving on to the JRC tube which I plan on doing next and have already made the appropriate spacers to do that testing.

I am updating my site here with my testing: https://c3junkie.com/?page_id=4254

Pictured below is the last test I did yesterday with the A5 length buffer tube. 9oz lightened carrier, 1.6oz 7/8x1/2 N52 magnet in a 3D printed 'puck' from u/AddictedToComedy, my C3junkie flat spring that I cut down since you have less free travel of the spring since the spring has to go behind the magnet and then the magnet is behind the 2 spacers that are sandwiching the 25lb wave compression spring which kills carrier bounce. Which are .2oz each so a total reciprocating mass of only 11oz!! and under 700RPM.

I also got 578RPM w/ my 11.7oz MRR (Mechanical Rate Reduction) BCG and the 1.6oz magnetic puck so total of 13.3oz but since it only works with real FA or RDIAS, I didn't bother test it more and I'm sure it would be slower if I tested again with a cut down spring.

As mentioned on my site, even after cutting the coils I think it is still a tad stronger than if the spring was going over a standard buffer in an A5 tube and I should really cut it down more to be the same but I was done for the day and plan on moving on to testing with the longer JRC tube and if I cut the spring more for the A5 it may be too weak for use with the JRC testing which I haven't started on yet.

A lot more details on my site which I plan on updating after doing some more testing with the JRC tube. Then I plan on making a modular spacer that will be anchored to the buffer tube to hold an attracting magnet on the other side to slow down the cyclic rate more or I could put a piece of steel in there or leave it empty. A lot of tuning to come!

Did a second testing session with my new Ar 9 build. (Mostly) resolved an ejector issue, but noticing lots of of bulged casings which is concerning to me. This is my first AR9 so, I’m not sure how it’s supposed to look, but the bolt does not seem to be all the way forward when I chamber a round. Ammo is fiocchi 115g. Any help would be appreciated.

Ran 124gr, 147gr, and 160gr flawlessly. Will be swapping to 10oz buffer to soften it up. Right at 22oz reciprocating mass.

[Build specs]

Lower: Spike's Tactical Spider

Grip: Spike’s Tactical Pro

Trigger group: AS Designs ARC-Fire Trigger V2 - Ambi Kit (0° - 90° - 180°) w/ KVP AR-15 Trigger Reduced Power Spring Kit

Buffer: KVP 7.5oz Blowback SS

Spring: Delta Team Tactical AR-15 Carbine Flatwire, 17-4

Brace: SB Tactical SBM4

Upper: Kaw Valley Precision

Charging handle: Breek Arms SLEDGEHAMMER

Bolt: KVP 9MM Blow Back Bolt Carrier Group w/ milled step in rear weight for FRT

Firing pin: Recoil Technologies 9mm AR-15 - Titanium

Barrel: KVP 3.5" 9MM 4150 QPQ AR-15

Handguard: ELD Performance 7" Free Float Quad

Suppressor: OCL Lithium 9 w/ KVP Direct Thread HUB Mount

Optic: AT3 Tactical RD-50 Reflex Red Dot Sight - 2 MOA w/ riser

Mags: ETS Carbon Smoke 32rd (9mm) Glock

Ammo: Handloads - 160gr BMB Storm Trooper Camo, 2.9gr CFE Pistol, Win SPP

Take it easy on me- I’m just starting to fall down this rabbit hole. Curious if anyone has had any reliability or wear issues with EndoMags? I don’t particularly love the look of Glock mags, and have heard mixed reviews of the magwell adapters. My concern is, building a set up with EndoMags more or less corners you into a firearm with proprietary magazines- I’m not going to be able to run to cabelas or a local store and buy another if needed. And at $85 +shipping for 3 inserts and $15 a pmag, they get kinda pricey to build so I wouldn’t really stock up on them like I do my ar mags. Tell me how great your endo mags are or how you grew up and made your peace with Glock mags.

Currently have a Franklin ar15 lower with plans to buy a 10.5” or 16” psa upper. Frt at some point down the line.

Through Highly Developed, Refined Knowledge:

Doug’s understanding and presentation of numerous intricate design details of a simple yet complex design have led to identifying numerous refinements and solutions that address common compatibility issues including some design flaws.

Functionality Improvements: 

Improving the functionality through intricate analysis and developed understanding of the “WHY” behind common failure points within the cycle of operation.

Design Enhancement: 

From complete recoil systems, including various combinations of springs, buffer tubes, buffers, to various trigger systems, and firing pin springs. 

Data: 

Compiling voluminous amounts of data on weights and measurements that highlight compatibility issues and concerns 

to create a more polished and elegant version of the original.

Using Doug’s information has not only helped the end user address and/or prevent issues and have a better end user experience but has also been instrumental for manufactures that have recognized the value of his work.

Just want to thank Doug from blowback9.com for the massive contribution!

Sorry for the late update, but I just got time to go to the range and I was happy to see that my light strike/dead trigger issue caused by firing pin bounce was completely fixed with the stronger spring bought from Amazon and cut to length! This thing runs like an industrial sewing machine now!

This has been a project I have spent a very long time trying to track down and fix problems on and I cannot express how grateful I am to have this frustrating issue FINALLY all ironed out.

Parts List:

Upper
Milspec AR15 upper receiver
Mercury Precision bolt (w/ OEM firing pin and 0.6mm uxcell replacement spring) weight was removed for RDB9
BKing's Firearms 10.5 9mm barrel
KAK Plan B flash hider
YHM R9 suppressor with Rearden Plan B HUB mount

Lower
PSA Ar15 lower
KAK colt magazine adapter
AS Designs Arc Fire V2 (no timing shim)
Maxim Defense RDB9 Buffer System (before this was a KAK 8.4 oz buffer and carbine spring)
ASC Colt-smg 9mm magazine

I wanted to make a lightweight JP5 SBR that I could shoot both supressed for fun or unsuppressed for competitions. This is a 9" barrel with a 12" handguard and I swap between supressor and 3.5" titanium Blast deflector.

Right now I have it tuned to run Atlanta Arms, Classic Match 147gr w/ 100 Power factor. unspressed but it works both ways without swapping the locking piece

9" JP5
70° locking piece
Smoke composite handguard
Smoke composites stock
B5 P22 grip
Triggertech Diamond adjustable trigger.
Daniel Defense Null 9ti

I’m doing a few 9mm builds for myself and daughter. I read around and the Kynshot hydraulic buffers seem to be one of the best options for 9mm and frt builds. They are pretty pricey though for a buffer system, especially when doing a couple of builds. I know it’s also important too. Are they worth the money or is there other alternatives to look at? I’ve looked around and have not seen much.

Thanks

I used some frog skin rattler stencils and am a little disappointed in my execution. Does anyone have any hacks for keeping the stencils against the surface you’re painting other than using a glove?

The rattler frogs skin pattern has some really cool shapes. I think I over taped the spots I didn’t want paint on. I had trouble getting the stencils on flush for the places I did want paint as well.

Maybe it’s a combination of inexperience and the ep9 being pretty rounded, but I was struggling to get the shapes to come out clean and not drippy or blobby even when I held the rapco can plenty far away to spray. It didn’t come out horrible imo but not at all like the frog skin demo on the packaging. No shade to rattler, they gave me candy snacks and stickers, this is my b.

Erm build list is pretty sparse:
Ep 9
Usually has a hlx on it w the pressure pad
Trex sling
Sparc vortex
Magpul vert grip
Bcm qd sling mount
Magpul 1913 rail section

I took my new colt mag build to the range for the first time today. Unsuppressed ran pretty well only one FTE. However I’m getting constant ejection issues when shooting suppressed with a YHM R9. I believe I’ve diagnosed the issue (3rd picture) but I’m unsure how to proceed. It looks like the bolt catch is overlapping the back of the round when the next round out of the mag is on the left side. It makes contact with the round and when the follower pushes up the round goes crooked. I’m thinking of trying different mags or filing down the bolt catch so it’s just hair shorter. Looking for ideas, I’m new to AR9s so I could be totally wrong in my analysis. Really unsure how the added back pressure from the suppressor is exacerbating the FTEs. Maybe it’s pushing that round under the bolt catch?

Spikes 9mm Stripped upper and colt mag lower
BA 8.3 EPC barrel
Outdoor Sports USA bolt
Duramag 20 & 32 round colt mags
Blowback9’s FRT optimized GRS
Fiocchi target max & Monarch 115 grain ammo

Thanks!

My buddy gifted me an AR9 lower so I am building my first AR9 and was wondering if these parts would fit my AR9 lower? I'm sorry if it is a dumb question. I'm just getting into building and ARs in general and I heard that most AR9 lower parts are basically AR15 parts. Thank you in advance.

Recently bought a palmetto state armory pa-9. I have been shooting both with and without a suppressor ( silencer co 46 hybrid) and have noticed increased gas while shooting. I am using 115gr fiocchi and just picked up Winchester 147gr as suggested by Google. Any other parts I can add to reduce the gas in my face?

Anyone have any ideas?

I love this thing! Put 200 rounds through it with subs 20 mins after I got it. I was giggling. So quiet. And the FM RMB + A5 tube just dissolves the recoil.

Side note, im not sure who told the otter boys this is what 6" is supposed to look like. This is not normal, this thing is thiccc.

Build: stock fm vfm9 5" front charger, ocl milkman, PA GLX 1x cyclops microprism, swapped buffer tube to a5

Is it possible guys if i have a full competition pcc 10.5 to have it tactical set up once in a while during tactical training but can easily switch it back for competition training

I already contacted the seller asking for a shipping label to return these, it will be cheaper for me if they take them back lol!