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Posted: 7/3/2025 2:47:33 PM EDT
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CMMG is having a 17.76% off sale, just in time for my 9mm upper build! Just ordered the 9mm Radial Delay Blow back bolt and receiver kit. Normal price is $424.95. Got it with free shipping and tax for $370. Amphibian and I have been going back and forth a bit on this build, and now I'm just waiting for his quote on a 4.5" barrel with a single feed extension. So, a shout out to Amphibian, great guy dealing with all my questions! Upper will be used on my 300 Blk SBR lower for now with Endomags. I'm going with the single feed extension so I have the option in the future to build out a 9mm specific lower and it'll function with Glock mags (Amphibian says standard M4 ramps are ok with Endomags, but not Glocks). Only downside, CMMG says shipping is within 15 to 30 days....meh. |
| That's awesome did you get the new type with the Fixed ejector or did you get the old style with the standard ejector? I think I purchased the updated upper and bcg for a little over $400 with a 10% coupon code. Amphibian is awesome, he assisted me with cutting some relief cuts in my new upper to accept scorpion mags. Between him and blowback 9 they make this sub-forum a learning paradise. |
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Originally Posted By tawoodii: That's awesome did you get the new type with the Fixed ejector or did you get the old style with the standard ejector? I think I purchased the updated upper and bcg for a little over $400 with a 10% coupon code. Amphibian is awesome, he assisted me with cutting some relief cuts in my new upper to accept scorpion mags. Between him and blowback 9 they make this sub-forum a learning paradise. Fixed ejector. I didn't see an option for the old, maybe they don't sell it anymore? Agree on Amphibian and Blowback 9, I've been soaking up all I can on their websites since this is my first foray into a 9mm upper. I didn't really want to go with a straight blowback and mess with all the crazy buffer doo-dads and anything roller delayed is too pricey (except maybe the Mat9, but I dunno about it) . This is just a toy, so I didn't want to drop a lot on it. Minus a handguard, charging handle and sight, I'm only into this thing for about $600. All the radial delay goodness for several hundred less than a complete CMMG upper. |
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Originally Posted By amphibian: Thanks for kind words... Speaking of Scorpion lower...I messed with this today. https://c3junkie.com/wp-content/uploads/2025/07/phase3-1.jpg I really don't care for side chargers but I was curious if I could make this work. I like what you did here. My immediate thought was this could also be accomplished the other direction to get a dual-charger:  CMMG BCG CMMG upper/modified (open gas tube hole at front to accommodate charging handle rod, angle rear of charging handle latch catch pocket) FM fore-end + charging parts Mil-spec or ambi charging handle/modified (plug hole for gas key w/pinned insert to mate w/fore charging handle rod)Essentially, the FM charging handle drives the standard charging handle from the front. I used this approach with my .22LR AR https://www.ar15.com/forums/ar-15/Forward-side-charging--22lr-Foxtrot-Mike---CMMG-frankenbuild/15-787041/ if you want to see pictures. OP, I think my journey through ARs was the opposite direction of yours. I started on the direct blowback PCCs and initially avoided all rifle calibers so I didn't have to learn the nuances of gas systems. Feeling like I'm moving against traffic, lol. May your build go well. And, yeah, BB9 & amphibian are quite helpful and knowledgeable. They are great resources. At some point I'm gonna want to talk to you, amphibian, about a barrel. So many builds, so limited time and money. |
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Originally Posted By PreacherOfGadget: I like what you did here. My immediate thought was this could also be accomplished the other direction to get a dual-charger: CMMG BCG CMMG upper/modified (open gas tube hole at front to accommodate charging handle rod, angle rear of charging handle latch catch pocket) FM fore-end + charging parts Mil-spec or ambi charging handle/modified (plug hole for gas key w/pinned insert to mate w/fore charging handle rod)Essentially, the FM charging handle drives the standard charging handle from the front. I used this approach with my .22LR AR https://www.ar15.com/forums/ar-15/Forward-side-charging--22lr-Foxtrot-Mike---CMMG-frankenbuild/15-787041/ if you want to see pictures. OP, I think my journey through ARs was the opposite direction of yours. I started on the direct blowback PCCs and initially avoided all rifle calibers so I didn't have to learn the nuances of gas systems. Feeling like I'm moving against traffic, lol. May your build go well. And, yeah, BB9 & amphibian are quite helpful and knowledgeable. They are great resources. At some point I'm gonna want to talk to you, amphibian, about a barrel. So many builds, so limited time and money. However those never went into production. The FM upper isn't machined for the traditional side charger and I could modify it but is a catch 22.... I think a lefty may not like having a traditional CH thinking that they don't want any gas leaking from the back. Like I posted above, I don't really like side chargers at all. I just did it to see if I could and maybe see if it is easier for my teenage son to charge. In handling it, I keep trying to reach for a rear mounted charging handle from so much muscle memory. If it isn't any easier for my son, I'm probably going to try to sell the whole thing. |
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So, a with all this 9mm stuff occupying me right now, why doesn't anyone make a gas operated 9mm? There was a fellow, Mike Garrow, back in 2019 created a 17HMR gas upper (used a combination of direct impingement and roller delay). I spoke with him a few times about a 9mm gas operated upper he was finalizing and was going to sell, but then the company folded when he got into a lawsuit with his CFO and founding partner. https://www.pewpewtactical.com/what-happened-garrow-arms-development-17hmr/ So, why no gas operated 9mm uppers? Is it a technical nightmare? Not enough gas to make it work right? Cost? I think if a 17HMR can operate on gas, 9mm should be able to. |
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Originally Posted By EDL: So, a with all this 9mm stuff occupying me right now, why doesn't anyone make a gas operated 9mm? There was a fellow, Mike Garrow, back in 2019 created a 17HMR gas upper (used a combination of direct impingement and roller delay). I spoke with him a few times about a 9mm gas operated upper he was finalizing and was going to sell, but then the company folded when he got into a lawsuit with his CFO and founding partner. https://www.pewpewtactical.com/what-happened-garrow-arms-development-17hmr/ So, why no gas operated 9mm uppers? Is it a technical nightmare? Not enough gas to make it work right? Cost? I think if a 17HMR can operate on gas, 9mm should be able to. I also had a gas piston operated Sig MPX and found it to be gassy and loud. I also had an RMW .45 gas operated and it was super smooth but it too got a bit too dirty for my tastes as it also had the port pretty close to the chamber. That said, it is my humble opinion that since the MP5 is considered the gold standard in the recoil impulse department and it doesn't use barrel with a gas port, I personally lean towards mechanisms that don't use a port. Now this is just pistol caliber lower pressure and there are some exceptions I would think a gas operated 10mm would do well. I also reload the same 9mm subsonic loads used in UZI's, MP5's and other SMG's where I am using a fast burning powder charge and want the powder to be burned up in short barrels fast. I don't think that carries over based on the recommended loads I've seen for the RMW 9mm upper. I am definitely not interested in making special 9mm for just one configuration either. I'd rather that all my 9mm guns can use the same ammo I load. |
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Originally Posted By EDL: So, a with all this 9mm stuff occupying me right now, why doesn't anyone make a gas operated 9mm? There was a fellow, Mike Garrow, back in 2019 created a 17HMR gas upper (used a combination of direct impingement and roller delay). I spoke with him a few times about a 9mm gas operated upper he was finalizing and was going to sell, but then the company folded when he got into a lawsuit with his CFO and founding partner. https://www.pewpewtactical.com/what-happened-garrow-arms-development-17hmr/ So, why no gas operated 9mm uppers?Is it a technical nightmare? Not enough gas to make it work right? Cost? I think if a 17HMR can operate on gas, 9mm should be able to. Short answer: to work reliably, the gas port would have to go through the barrel nut and barrel extension (see image below). Once you are taking off gas forward of the barrel nut on a standard AR upper with a 9mm barrel, the gas volume & pressure are too low to cycle the AR's system reliably, even with a reduced mass carrier and a buffer w/weights removed. There ARE gas powered AR uppers (Sig MPX 9mm comes to mind), but the upper, handguard, barrel, receiver, buffer/spring system, bolt carrier, and gas system are completely proprietary to enable taking the gas off close enough to the chamber to cycle the a lower-mass carrier with different springs than a standard AR. Very few parts are compatible with standard AR upper parts. Notice how the gas block/barrel extension are the same part to achieve a take-off point just fore of chamber. (not my image, found w/google) 
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Ok, makes sense. I thought maybe standard pistol length gas would do it, but I guess not. I like the idea of the 10mm gas operated. Man, wish I had the machines to make this kind of stuff. I wanted to do it after retiring from the military, but I had a family to feed and college for two kids to pay for. I've never gotten into wildcats, but I can think of several I'd like to have created! |
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Its so funny you say that @Amphibian. You mentioned gas operated 10mm. I've been working on Gas Piston 10mm and 9x25 Dillon uppers to be fed by the same CMMG lower. I've almost got the 9x25 Dillon working completely but it still needs a little more oomph for locking back on LRBHO. The 10mm on the other hand is going to require a lot of work as I want it to function on all 10mm loads by just adjusting the gas piston. I was going to do a full write up on it when I get them both running well. Here's a couple videos of me testing both. The 9x25mm was easier because all 9x25 Dillon is hot hot hot, while the 10mm can go from anemic plinking rounds to much hotter hunting loads. 9x25 Dillon 124gr, 10.5" RMWXtreme barrel, AA Micro Adjustable Gas block, 0.4" Titanium Piston/Op Rod, A5 Buffer tube, Tubbs LW Spring, 0.8oz Buffer 9x25 Dillon Gas Piston Test 1 10mm 180gr, 10.5" Macon Barrel, AA Micro Adjustable Gas block, 0.5" Titanium Piston/Op Rod, A5 Buffer tube, Tubbs LW Spring, 0.8oz Buffer. 10mm Gas Piston Test 3 (not quite there yet) |
Don't have an MP5, but there are plenty of vids on YT comparing the various designs to it. Seems MP5 is still considered the gold standard. Radial Delayed Blowback VS Roller Delayed Blowback! |
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Originally Posted By texaspaulhouston: So you guys who have MP5s and RDB FE does the recoil feel similar or is the MP5 still better in reducing recoil. The cost of MP is just too much compared to a CMMG upper on a AR-15 lower. I have full auto MP5's but with my tuned CMMG RDB I think it is smoother than my MP5 and everyone that has shot my tuned CMMG RDB's side by side my MP5 has agreed. This goes for novice and expert shooters. One of my customers is also a federal agent who was issued an MP5 when they were in service as well but now he shoots my setup documented on my site here: https://c3junkie.com/?page_id=1733 On that link, I mentioned that I do NOT think a stock CMMG RDB is that smooth. I also go over that here documenting my old config: https://c3junkie.com/?page_id=2642 The video below, his custom Banshee is my OLD config:  Ultimate 9mm PCC Comparison PART 2 | CMMG Dissent (CMMG Dissent vs Banshee vs Sig MPX vs MP5) |
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Originally Posted By EDL: Don't have an MP5, but there are plenty of vids on YT comparing the various designs to it. Seems MP5 is still considered the gold standard.  https://www.youtube.com/watch?v=zbiP0Zsbb8gChanging to the buffer, buffer tube and spring setup I recommend, you will then get to MP5 smooth. Don't get me wrong, I will always have the highest respect for the MP5 as it is a proven classic. That said, for the SMG matches I go to and just for plain fun, I prefer my tuned CMMG RDB for the following reasons:
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Yeah, I just up and decided I wanted a 9mm upper, and went down this rabbit hole real quick. Honestly, an FRT is what got me on it. Since I reload, even though my 300 Blk rounds are a bit cheaper than commercial ammo, they're still expensive compared to what I load 9mm for. Right now with my on-hand components, I'm reloading 9mm for about 15 cents a round vs about 32 cents for 300 Blk. I wanted something that I could hit the giggle switch and not stress too much over how much $$$ I am blasting down range, hence, the 9mm. I first looked into a 22LR upper, but getting one of those to run with an FRT seems to be very hit and miss, lots more issues than the 9mm. So here I am.... |
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Originally Posted By texaspaulhouston: So you guys who have MP5s and RDB FE does the recoil feel similar or is the MP5 still better in reducing recoil. The cost of MP is just too much compared to a CMMG upper on a AR-15 lower. I have one of just about every kind of operating system and the MP5 is still king, but the FE RDB does open up a lot of possibilities with springs and buffers that you won't find with anything else. |
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Curious if there are any updates on the Broad River SD setup, long-term use. I placed my order about five weeks ago and am still waiting (6-8 weeks for a complete upper but I'm hearing even longer delivery times). Was sort of an impulse buy and I went radial delayed before doing a lot of research. I then stumble upon the ejector issues with the CMMG bolt. Curios if the BR setup would work with the external ejector bolt and upper from CMMG. I reached out to BR and never got a response. If you run an FRT in one of these I can see the necessity to change the spring every range session. |
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Originally Posted By Ape_Factory: Curious if there are any updates on the Broad River SD setup, long-term use. I placed my order about five weeks ago and am still waiting (6-8 weeks for a complete upper but I'm hearing even longer delivery times). Was sort of an impulse buy and I went radial delayed before doing a lot of research. I then stumble upon the ejector issues with the CMMG bolt. Curios if the BR setup would work with the external ejector bolt and upper from CMMG. I reached out to BR and never got a response. If you run an FRT in one of these I can see the necessity to change the spring every range session. I made this post a few days ago which is relevant to your post: https://www.reddit.com/r/AR9/comments/1lya7lb/comment/n321giw/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button I'm too lazy to re-type so I'll paste it again below: You still see posts where their barrels are hit or miss. I reference some of those threads on my site here: https://c3junkie.com/?page_id=1882 As you can see from that link I have been modifying straight blowback barrels for the CMMG RDB system and also having a run of stainless barrels made now. Another issue I have been seeing is that some people are having reliability issues with weaker ammo. I see 115Gr sometimes being too weak. Some points to think about: 1. The original 9mm CMMG RDB BCG came with a 50 degree bolt which could handle weak ammo but I thought it was sub-optimal for use with a muzzle can 2. I ended up using a .40SW 60 degree bolt for 9mm as I run like 99% suppressed but note that the impulse is so soft a fixed ejector is required which I had since I did custom work to do that. 3. The Dissent 9mm is fixed ejector and logically came with a 55 degree bolt since it is bufferless and has less total mass than an RDB configuration that uses the buffer tube. 4. Then they release the FE Banshee with the same bolt they are using in the Dissent....I thought that was odd and anticipated that some people would have issues if not running a suppresssor and using weak ammo and here we are...I see exactly that scenario. Note I also see complaints with people running SD setups as well. I don't have that issue with my custom PhaseII: https://c3junkie.com/?page_id=1733 since I have an aluminum CE (carrier extension), I can just run it hollow and bring my reciprocating mass down lower than what is possible with the new FE Banshee BCG since that is all steel. I would really like to see CMMG release bolts with different angles to allow for tuning. I would love to go back to a 60 degree bolt...if they made a FE Banshee retrofit kit for .40SW, I would buy it just to get that bolt. Likewise, people running weak ammo, or an integral would probably want to go with a 50 degree bolt. What I probably failed to elaborate on is I am using my 'ARS' documented here: https://c3junkie.com/?page_id=2757 Depending on what ammo you are using, you may not be able to use the FE Banshee with the BRT barrel with that buffer / tube / spring combo that I like. You may have to go down to an RB5005 or lighter or something different all together to get the reciprocating mass down. |
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Barrel from Amphibian and the CMMG kit arrived today! Still waiting on a few parts before I can assemble it all, but should be here soon. The bolt is a 55 degree in the kit (I assume this is the newer Banshee FE based kit?). Also, the bolt has no spring to push it out, I assume that was one of the older original RDB set ups? I seem to recall that detail in videos I watched a while back. The firing pin has a spring, so that's different than the standard floating pin in the AR. So, more waiting for the rest of the parts.... |
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Originally Posted By EDL: The bolt is a 55 degree in the kit (I assume this is the newer Banshee FE based kit?). Also, the bolt has no spring to push it out, I assume that was one of the older original RDB set ups? I seem to recall that detail in videos I watched a while back. The firing pin has a spring, so that's different than the standard floating pin in the AR. Yep, That is the new FE kit. The new bolt is labeled 55 and no longer has the spring. I will say it is softer shooting than my original RDB but it cannot cycle 115gr 9mm ball without a suppressor and sometimes it still doesn't cycle even with it. |
| That's ok, won't be using 115 grain with it anyway. 147 grain and suppressed. Handguard, charging handle and Endomag are sched to arrive Friday, then I can assemble and test! I'm sure I'll need to do some work with the buffer in my SBR lower. Will have to find a happy medium that'll work for both the 9mm upper and the 300 Blk upper, but I do have a Superlative Arms AGB on the 300, so that'll allow a little leeway to tune as well. |
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Originally Posted By EDL: That's ok, won't be using 115 grain with it anyway. 147 grain and suppressed. Handguard, charging handle and Endomag are sched to arrive Friday, then I can assemble and test! I'm sure I'll need to do some work with the buffer in my SBR lower. Will have to find a happy medium that'll work for both the 9mm upper and the 300 Blk upper, but I do have a Superlative Arms AGB on the 300, so that'll allow a little leeway to tune as well.
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I will look into that set up. The A5 tube is only, what, 1/2" longer than a carbine tube? I've read your website, but there is so much, I'll go back to the links you provided for sure. The rest of the parts came in today while I was at work (just got home), so tomorrow I'll get it assembled. Need to pick up some 147 grain ammo though, all I have right now is 115 grain. Will order some 147 grn bullets from RMR, but need to decide between round nose or truncated cone. Maybe some of each to see if there is any difference in feeding and/or accuracy. I have a ton of WSF powder I bought a few years ago for cheap. Should be able to get 980-1000 FPS out of it with 147's. |
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Originally Posted By EDL: Will order some 147 grn bullets from RMR, but need to decide between round nose or truncated cone. Maybe some of each to see if there is any difference in feeding and/or accuracy. I have a ton of WSF powder I bought a few years ago for cheap. Should be able to get 980-1000 FPS out of it with 147's. https://www.rmrbullets.com/shop/bullets/pistol/9mm-355/9mm-147-gr-rmr-full-metal-jacket-round-nose-bullets-new/ There are also several threads you can find discussing this. I also mention it on my website: https://c3junkie.com/?page_id=2324 I finally burned through all of my RMR 9mm projectiles and not buying anymore. I have run throating reamers in some barrels but I don't want to do that with every 9mm gun I own. Easier to just stop using those bullets. I've been happy with bullets from American Reloading which are typically cheaper than RMR but the options they have on hand are like $60 delivered and pulled. I usually wait till I can get blems for under $50 delivered which I don't see for 147Gr right now. I stocked up on those 155Gr and Norma 158Gr when they had them for cheap. The Norma's were pulls but I just load them so the COL matches the pull mark. |
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Well, she's assembled, but had a small boo-boo.... The aluminum barrel nut is round and has holes that you need a wrench with lugs. I used my Trueglo armorer's wrench and right before it got the target of 40 ft-lbs one of the lugs on the wrench snapped off which in turn the sudden slip and grab of the other two lugs caused one of the lugs to bust through the side of the barrel nut. All in all, it turned out OK, I just had to file a couple spots. Once assembled, you can't see it. Function checked and it works perfect with the binary trigger. CMMG Radial Delay upper receiver kit 5" barrel from Amphibian with single feed ramp extension, threaded 5/8x24 SiCo Omega 36M suppressor 9" handguard Ares V-2 circle dot reflex sight Sitting on my registered SBR lower with: Franklin Armory binary trigger Fab Defense GL-Core-S buttstock Fab Defense Gradus low angle grip. Will report back later once I get chance to run some ammo through it, etc. 
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Originally Posted By EDL: Interesting, was not aware of the issues with RMR. I buy their 115 grain and haven't had any issues (then again, I don't have a Gen 5 Glock, but they load and run fine in the CZ P-10F). I'll check out the other brands then. |
| If you have a 9mm Blowback weapon test them together and you'll see a real difference in recoil and enjoyment. I bought an AR-V parts kit years ago from PSA hoping to put in all the CMMG hardware only to find out the lower is insanely proprietary and would not accept any other bolt but PSA's own blowback one. I was going to get rid of it, but the wife decided she wanted it so I built it up for her using BB9's GRS. While the GRS tames some of the recoil it is no where near as smooth as Amphibian's ARS set up. |
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I don't have a straight blowback, but I understand roller and radial delay vs straight blowback, that's why I went the route of the CMMG and RDB. Been considering a 9mm upper for a while, but didn't want to pay the price for roller delay and didn't want to pay $1,000+ for a CMMG complete upper. I was reading BB9's stuff on his page, but I still didn't want to do straight blowback. So, I kind of backed off on it and was just sort of going along, reading, etc. Wasn't really seriously considering on one right now, then BCA came out with their bufferless and that got me interested again. Then Amphibian replied and pointed me to CMMG's retrofit kit. Price was right with the sale they had, his barrel was right, so here I am! Total invested, including the handguard, sight, endomag, and charging handle was a tick under $725. Watching the weather forecast now (anxious!), and not looking great at this point for Wed. and Thurs., at least not for a range trip, but I can go out back behind my barn and at least function test with some ammo and get it sighted in. Would prefer to go to range so I can take other stuff to make it worth the trip (I have some 6.5 Grendel loads to work up and need to burn some commercial 350 Legend for the brass), but, gotta do what I gotta do. |
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Originally Posted By amphibian: If you are planning on swapping between 9mm and .300BLK on the same lower, I think you would be fine with my 'ARS' https://c3junkie.com/?page_id=2757
+1 for this setup. I use the same SBR lower with different uppers in 300blk, 5.56, and 9mm and never have to make any adjustments. It just works. |
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Originally Posted By EDL: So, would you go 300 Blk TUBB spring, or 5.56? "Flat springs Not all the same. Some like the Strike Industries are too tight for the RB5007. I like the Tubb 300BLK for getting the full auto cyclic rate down for 9mm/40SW CMMG RDB configurations. It is like 30RPM slower, however the spring is typically too weak for reliable operation for a 5.56 mag fed configuration. The Tubb 556 will work with both calibers but is a little fast for my tastes when used with the CMMG RDB 9mm/40SW configurations. I have found that the Neverwear Warthog flat spring is a good compromise between the Tubb 300BLK and Tubb 556 where it seems to work fine with both my 9mm/40SW CMMG RDB configurations with just about the same cyclic rate as the Tubb 300BLK spring but still work with 5.56 mag fed uppers." Direct link https://www.neverwearsprings.com/index.php/product/ar15-warthog-flat-wire-buffer-spring-1-spring-26-00-ea/ Apex had them for $20 but out of stock: https://www.apexgunparts.com/ar15-m16-flat-buffer-spring-new-us-made.html |
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Sorry on no updates. Was all set to give it a try, but wasn't able to find the 9mm end cap for the suppressor. Then work has been a big beotch that last couple weeks, but I finally found the end cap. Of course, my day off and it's been raining, so going to wait for it to stop before I run out behind the barn and give her a try. Don't have the buffer changed out yet, but I'm going to give it some shots with the carbine set up, mainly for basic function check. Picked up a couple boxes of 147 grain Aguila ammo (only 147 grain I could find at three local shops). Sitting here eating right now, but after, will plunk test the ammo, then if good, start with a single round in the endomag to check feed and LRBHO functionality. Then proceed from there. |
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Ok, just came in from testing. I think the carbine spring doesn't have enough arse, seems to struggle chambering the first round when charging. Almost every time, the first round will fire, but then it doesn't chamber the next round, but, after that, recharging it without dropping mag, it then runs fine. LRBHO works. I use a 30 round Pmag with an Endomag (cut to be a 30 rounder). Most I've put in at once as of right now is 12 rounds. My son ran it in binary mode, and again, after initial charge, first round goes bang, then nothing, it misses chambering the second round. Recharge it, then it ran the remaining 11 rounds in binary mode without issue. I followed with 10 rounds in binary mode and it ate through 8 rounds and then failed to feed the last two rounds. These are small issues that I'm sure I can work through once I get the rest of the A5 tube/spring/kynshot buffer parts in. Still, I was giggling with how quiet this thing is. It's quieter than my 300 black. It does run really dirty though, half a box of ammo and she's filthy, but I don't care....she's my kind of dirty girl! Here's a video of my son running through the 11 round binary mode (not sure why my phone captured the goofy audio though): https://www.youtube.com/shorts/HHPArWDq8Uw |
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Amphibian, I have a question. Went back to your page on buffers and you mentioned the RB5005 as a good alternative to the 5007 if you want to keep/use a carbine length tube. The question is, how much difference is there with the 5005 in a carbine tube and a good flatwire spring vs the A5 tube, flatwire spring and 5007? Is it significant? Not a deal breaker either way as I have an A5 tube, the Neverwear spring you suggested and a 5007 on order, I am just curious more than anything. Pretty stoked for those parts to get here as the way it's currently configured with the standard carbine tube, spring and buffer it shoots pretty darn soft, very little muzzle rise and not much on the recoil (and I'm still giddy as a kid on Christmas at how quiet it is). |
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Originally Posted By EDL: Amphibian, I have a question. Went back to your page on buffers and you mentioned the RB5005 as a good alternative to the 5007 if you want to keep/use a carbine length tube. The question is, how much difference is there with the 5005 in a carbine tube and a good flatwire spring vs the A5 tube, flatwire spring and 5007? Is it significant? I was actually trying to get away from the 5007 thinking I wanted to get the reciprocating mass down but even compared to the 5005 I could tell it was still smoother. See what I put on my site here: https://c3junkie.com/?page_id=2757 "Now if you look at my live fire video which is in the link above and I have pasted below for convenience and watch the first 5 seconds you can see the buffer body move forward on that initial recoil impulse. The RB5007 is heavier than say an RB5005 but that heavier mass helps with that initial recoil impulse" It is noticeable to me but everyone is different. Case in point, I was at the range with two other friends. One is federal LE officer agent and he couldn't tell a difference. He is also a really big guy while myself and friend could clearly feel a difference. We were comparing two different PhaseII builds at that time with different CE configurations....but even then we had to have both setups ready to go and shoot them side by side immediately to notice the difference. Since you are not running my PhaseII, you are most likely not going to be using an extended stroke setup. The BCG will most likely be bottoming out in the buffer tube. That said, I would think that you would want more mass/inertia moving forward on that initial impulse that I mentioned earlier to spread that impulse over a longer period of time. |
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Sorry to hijack thread for a sec. First off I love AR9's and read all these threads. Thanks OP for doing the write up. Quick question for @amphibian or anyone else. I have a couple buffers I want to take apart to make a H3 buffer but I am struggling to get the plug out of the buffer. Any tips to get it out? And anyone using the Exomags? |
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Originally Posted By networkguru: Sorry to hijack thread for a sec. First off I love AR9's and read all these threads. Thanks OP for doing the write up. Quick question for @amphibian or anyone else. I have a couple buffers I want to take apart to make a H3 buffer but I am struggling to get the plug out of the buffer. Originally Posted By networkguru: Sorry to hijack thread for a sec. First off I love AR9's and read all these threads. Thanks OP for doing the write up. Quick question for @amphibian or anyone else. I have a couple buffers I want to take apart to make a H3 buffer but I am struggling to get the plug out of the buffer. Any tips to get it out? And anyone using the Exomags?  I discuss the Exomags here: https://c3junkie.com/?page_id=598 As I posted there, I have had issues with them swelling and I'm seeing on Reddit, others having the same problem. I haven't kept up to see if it has been resolved yet. I also posted this before. As much as I think Glock mags are ugly, they do work and to me the most forgiving if have some setup that may sometimes not travel back as far as required as the other mag feeding options.  |
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Originally Posted By amphibian: I used to use soft jaw pliers like the Knipex ones or worst case squeeze them in a vise to them out....but I typically don't mess with those buffers anymore. https://c3junkie.com/wp-content/uploads/2024/07/CMMG-9mmRDB-Mag-Options.jpg I discuss the Exomags here: https://c3junkie.com/?page_id=598 As I posted there, I have had issues with them swelling and I'm seeing on Reddit, others having the same problem. I haven't kept up to see if it has been resolved yet. I also posted this before. As much as I think Glock mags are ugly, they do work and to me the most forgiving if have some setup that may sometimes not travel back as far as required as the other mag feeding options.https://c3junkie.com/wp-content/uploads/2025/05/9mm-Mag-Options.jpg I'm having issues with them swelling as well, and I hope they make a gen 2 with steel feed lips. |
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