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Originally Posted By Jeeps-And-Guns: If I was to go with the roller delayed buffer, I would have to also get a new barrel and bolt. So the buffer system, bolt, and barrel all together is going to far exceed the cot of the cmmg FE kit. So sadly, the FE retrofit is going to be my cheapest option. My current upper looks to be pretty much standard AR flat top, so I can at least reuse that with other projects/builds, leaving only the old spring ejector BCG as trash. So at least there is that. I sold my .40SW setup which would killl ejector springs at about every 800 rounds. I also bought the .45 bolt repair kit to do a .45 build which I still have.....I haven't had ejector spring failures with .45 but don't shoot it much. I have had a few people buy barrels from me to do their own 'builders kits' in conjunction with the current retrofit kits. |
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Originally Posted By amphibian: I already did that when the Maxim was released, see my post below from 7/16/2023: https://www.ar15.com/forums/AR-15/-ARCHIVED-THREAD-Maxim-Defense-RDB-review/15-780933/?page=7  https://www.youtube.com/watch?v=FI5LMEszpxMOriginally Posted By amphibian: Originally Posted By Alien: I got the 5oz Maxim buffer and I'm waiting until my next range trip the weekend after next to try it out with the heaviest action tuning kit weight. Has anybody tried the CMMG Radial Delayed Blowback BCG with the Maxim Defense Roller Delayed Buffer? I was thinking that if my issue is that the BCG is moving too fast, then the Roller Delayed Buffer might slow it down to a reliable velocity without further increasing the reciprocating mass (which defeats the whole purpose of the Radial Delayed Blowback system), but I'm hesitant to drop another $180ish on a buffer after already spending $80 on the 5oz PDW buffer. I'll obviously wait to see how well it works with the 5oz buffer before spending additional money, but wasn't sure if this would muck things up. https://www.ar15.com/forums/AR-15/-ARCHIVED-THREAD-Maxim-Defense-RDB-review/15-780933/?page=7 https://www.youtube.com/watch?v=FI5LMEszpxMThat's odd that it was so much louder with the Maxim buffer. Do you have any idea why it was louder if it should be slowing down the system even more? My Radial Delayed Blowback gun with the heaviest weight in the buffer, Q Shorty stock w/ 5oz buffer, and my YHM R9 (which is decent, but not the best) is laughably quiet with my when shooting AAC 147gr. My brother didn't bring out his MP5s for me to compare it to, but we were literaly laughing about how absurdly quiet it was. Since the fixed ejector upper is now a thing and I would like to be able to reliably shoot self defense ammo in it without it having failures to eject, I'm probably going to get one. Do you think you are you able to swap in a Scorpion lower easily now like any of the ones made by NFA, Wraithworks, Daniel Defense, Evolution X Defense, (I swear I saw another one that can be paired with a Matador Arms upper) etc. I've only got 6 endomags for my CMMG RDB gun and hate the idea of spending another $140+ for 3 mags at a time, but I'd like to be able to use real SMG style mags that don't cost an arm and a leg. |
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Originally Posted By Alien: @amphibian That's odd that it was so much louder with the Maxim buffer. Do you have any idea why it was louder if it should be slowing down the system even more? My Radial Delayed Blowback gun with the heaviest weight in the buffer, Q Shorty stock w/ 5oz buffer, and my YHM R9 (which is decent, but not the best) is laughably quiet with my when shooting AAC 147gr. My brother didn't bring out his MP5s for me to compare it to, but we were literaly laughing about how absurdly quiet it was. Originally Posted By Alien: @amphibian That's odd that it was so much louder with the Maxim buffer. Do you have any idea why it was louder if it should be slowing down the system even more? My Radial Delayed Blowback gun with the heaviest weight in the buffer, Q Shorty stock w/ 5oz buffer, and my YHM R9 (which is decent, but not the best) is laughably quiet with my when shooting AAC 147gr. My brother didn't bring out his MP5s for me to compare it to, but we were literaly laughing about how absurdly quiet it was. Since the fixed ejector upper is now a thing and I would like to be able to reliably shoot self defense ammo in it without it having failures to eject, I'm probably going to get one. Do you think you are you able to swap in a Scorpion lower easily now like any of the ones made by NFA, Wraithworks, Daniel Defense, Evolution X Defense, (I swear I saw another one that can be paired with a Matador Arms upper) etc. I've only got 6 endomags for my CMMG RDB gun and hate the idea of spending another $140+ for 3 mags at a time, but I'd like to be able to use real SMG style mags that don't cost an arm and a leg. Note there is no Scorpion lower that is designed to work with the CMMG RDB. I've put a lot of work into mine above. The feed ramp must be modified if you expect any FP or HP round to work or it will slam into it. Mine still isn't 100%. I am waiting on trying a different extension with a different feed ramp and if that doesn't work I may have to throw in the towel....however there are some people in this thread that say theirs are working. https://www.ar15.com/forums/ar-15/New-NFA-S-9-Lower--Scorpion-mags---Pics--review-and-build-in-progress-with-CMMG-RDB/15-754694/ |
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Originally Posted By amphibian: I never got too invested in the spring loaded ejector Banshee's. I had (3) CMMG RDB setups. (2) 9mm and (1) .40SW. I converted my 1st 9mm to use my custom fixed ejector, then sold that with the disclaimer that the bolt may break. I sold my .40SW setup which would killl ejector springs at about every 800 rounds. I also bought the .45 bolt repair kit to do a .45 build which I still have.....I haven't had ejector spring failures with .45 but don't shoot it much. I have had a few people buy barrels from me to do their own 'builders kits' in conjunction with the current retrofit kits. Originally Posted By amphibian: Originally Posted By Jeeps-And-Guns: If I was to go with the roller delayed buffer, I would have to also get a new barrel and bolt. So the buffer system, bolt, and barrel all together is going to far exceed the cot of the cmmg FE kit. So sadly, the FE retrofit is going to be my cheapest option. My current upper looks to be pretty much standard AR flat top, so I can at least reuse that with other projects/builds, leaving only the old spring ejector BCG as trash. So at least there is that. I never got too invested in the spring loaded ejector Banshee's. I had (3) CMMG RDB setups. (2) 9mm and (1) .40SW. I converted my 1st 9mm to use my custom fixed ejector, then sold that with the disclaimer that the bolt may break. I sold my .40SW setup which would killl ejector springs at about every 800 rounds. I also bought the .45 bolt repair kit to do a .45 build which I still have.....I haven't had ejector spring failures with .45 but don't shoot it much. I have had a few people buy barrels from me to do their own 'builders kits' in conjunction with the current retrofit kits. Never got too invested.... Lists 4 different setups... 
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Originally Posted By amphibian: Just released: https://cmmg.com/fixed-ejector-retrofit-kit-9mm https://cdn11.bigcommerce.com/s-7ngaea0tdq/products/2569/images/9109/99BA69C-AB_1__17361.1745420686.1280.1280.jpg?c=1 You can see how the fixed ejector is secured to the upper (just like the Dissent). Bolted from the inside of the upper. https://cdn11.bigcommerce.com/s-7ngaea0tdq/products/2569/images/9110/99BA69C-AB_2__93807.1745421140.1280.1280.jpg?c=1%22 Of course, when I finally grumble about it enough and break down to buy it, it is now backordered. Looks like a shit ton of people must be ordering these kits. That probably tells you something. |
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I just went through the entire thread looking to see if there was a concensus on why the ejector springs were failing and there were a few theories ranging from blowback 9mm vs gas operated 5.46, headspace and extractor claw geometry. Did anyone ever prove what the problem was? If the fixed ejector doesn't weaken the bolt enough to cause long term problems, great. But it would be nice to figure out the spring ejector problem to enable use with a broad range of upper receivers. I just can't wrap my head around why the spring would be breaking in the first place. Could something be driving the ejector pin deeper into the bolt than flush? If so, could a spring guide "tail" on the back of the ejector pin that only allowed it to compress flush with the bolt face be the solution? ETA maybe the theory on headspace really is the correct answer. If there is excessive headspace, the base of the cartridge will be held away from the bolt face by the ejector, to the extent that the extractor claw and headspace allow. This is then violently slammed back upon firing, and possibly if it's fast enough, with enough inertia to drive the ejector pin as far into to bolt as it's retaining pin will allow. AI has this to say about very rapidly compressing a spring: Attached File It seems like the fixed ejector is the only truly practical solution for a delayed blowback gun. But then you get back into the question of how much the ejector slot weakens the bolt. Maybe instead of cutting the slot through the bolt face, they should have had the fixed ejector interact with the back of a pin with a return spring in the original bolt face location. This would keep the bolt face strong and still retain the benefits of a fixed ejector. |
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Originally Posted By Jeeps-And-Guns: Of course, when I finally grumble about it enough and break down to buy it, it is now backordered. Looks like a shit ton of people must be ordering these kits. That probably tells you something.  |
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Originally Posted By Jambalaya: But then you get back into the question of how much the ejector slot weakens the bolt. As I posted before, and on my website: https://c3junkie.com/?page_id=2642 Using the .40SW bolt used in 9mm had such a soft recoil impulse a fixed ejector was required while a new spring loaded ejector just wouldn't work at all. I see this also in some integral builds I've done for people....running weak loads plus a ported barrel results in a very soft impulse and just not reliable with the spring loaded ejector. Take the same ported barrel, ammo, buffer spring etc and change to my 'PhaseII' (https://c3junkie.com/?page_id=1733 ) build and it runs.  |
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Originally Posted By amphibian: I personally think it is all a moot point since CMMG redesigned the bolt (obviously w/ an accompanied carrier as well) to move the cam pin hole away from the slot. I'm pretty confident the new bolt design isn't going to break. The fixed ejector definitely increases the operating window. As I posted before, and on my website: https://c3junkie.com/?page_id=2642 Using the .40SW bolt used in 9mm had such a soft recoil impulse a fixed ejector was required while a new spring loaded ejector just wouldn't work at all. I see this also in some integral builds I've done for people....running weak loads plus a ported barrel results in a very soft impulse and just not reliable with the spring loaded ejector. Take the same ported barrel, ammo, buffer spring etc and change to my 'PhaseII' (https://c3junkie.com/?page_id=1733 ) build and it runs. https://c3junkie.com/wp-content/uploads/2024/02/bolt-comparison2.jpg Originally Posted By amphibian: Originally Posted By Jambalaya: But then you get back into the question of how much the ejector slot weakens the bolt. As I posted before, and on my website: https://c3junkie.com/?page_id=2642 Using the .40SW bolt used in 9mm had such a soft recoil impulse a fixed ejector was required while a new spring loaded ejector just wouldn't work at all. I see this also in some integral builds I've done for people....running weak loads plus a ported barrel results in a very soft impulse and just not reliable with the spring loaded ejector. Take the same ported barrel, ammo, buffer spring etc and change to my 'PhaseII' (https://c3junkie.com/?page_id=1733 ) build and it runs. https://c3junkie.com/wp-content/uploads/2024/02/bolt-comparison2.jpg Yeah I took a look at your site after making that post last night and I see that you also looked into making spring guides with nails, so that answers that question. Looks like you really put in a lot of thought and documented it well. I guess I'll just be happy with a fixed ejector Banshee when they come back in stock. I just wish they would make a (left) side charging upper for them. |
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Well I broke down and ordered the FE upgrade kit from CMMG. I got it for just over $400 with 10% off. I will say I'm going to have to modify the new FE upper though if I wish to continue the use of Scorpion mags. Right now I am using a KS47 upper but relying on the spring loaded ejector. I wonder if CMMG is going to bring out a .40sw version of the FE upgrade as I'd like to get my hands on one of their 60 degree angle bolt heads to try and replicate Amphibian's super smooth 100% build. Time will tell I guess, until then I'll just have to make due. |
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Originally Posted By amphibian: Just released: https://cmmg.com/fixed-ejector-retrofit-kit-9mm https://cdn11.bigcommerce.com/s-7ngaea0tdq/products/2569/images/9109/99BA69C-AB_1__17361.1745420686.1280.1280.jpg?c=1 You can see how the fixed ejector is secured to the upper (just like the Dissent). Bolted from the inside of the upper. https://cdn11.bigcommerce.com/s-7ngaea0tdq/products/2569/images/9110/99BA69C-AB_2__93807.1745421140.1280.1280.jpg?c=1%22 I had forgotten all about my 9mm AR. I haven't touched it since they sent the new parts. I had moved on to other projects. $425 doesn't seem too bad... I checked around real quick to see if they had the kits at Optics Planet or any of the places I usually have coupons for. No joy. I'll probably wait for a sale or something, but it's nice to know that they finally have the option for those of us that have held onto our old models for so long. |
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Originally Posted By Joker23: I had forgotten all about my 9mm AR. I haven't touched it since they sent the new parts. I had moved on to other projects. $425 doesn't seem too bad... I checked around real quick to see if they had the kits at Optics Planet or any of the places I usually have coupons for. No joy. I'll probably wait for a sale or something, but it's nice to know that they finally have the option for those of us that have held onto our old models for so long. |
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Took my RDB 9mm out again this past weekend. Started having failures to eject every single round right off the bat after not having any issues last time. Empty cases were stuck to the bolt! On a whim, I doused the bolt carrier and bolt/bolt face with CLP to get oil into the ejector channel. It blew nasty black oil all over me while shooting it, but it started working 100% again.  I've never had to do that with any other gun ever but remembered some people swear by that trick when their gun is malfunctioning (this is the first time I've ever had a problem AR). I'm just going to get the FE upgrade before I start shooting again in the fall now that it's too hot. |
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Originally Posted By Jambalaya: I just went through the entire thread looking to see if there was a concensus on why the ejector springs were failing and there were a few theories ranging from blowback 9mm vs gas operated 5.46, headspace and extractor claw geometry. Did anyone ever prove what the problem was? Originally Posted By Jambalaya: I just went through the entire thread looking to see if there was a concensus on why the ejector springs were failing and there were a few theories ranging from blowback 9mm vs gas operated 5.46, headspace and extractor claw geometry. Did anyone ever prove what the problem was? I am not an expert on ARs by any stretch of the imagination, but something I noticed that I wondered about. I have never changed an ejector spring before. When CMMG sent me new springs for the ejector and extractor (along with an extractor buffer), I had to pull the ejector spring out, it didn't fall out. The spring was so caked with crud, it looked like a pin more than a spring. With a regular DI AR, the gas comes through the gas tube and into the carrier key. Maybe the gas is directed different places/a different way than with the RDB system? Maybe all that crud finds its way into the ejector spring channel? Originally Posted By Alien: Took my RDB 9mm out again this past weekend. Started having failures to eject every single round right off the bat after not having any issues last time. Empty cases were stuck to the bolt! On a whim, I doused the bolt carrier and bolt/bolt face with CLP to get oil into the ejector channel. It blew nasty black oil all over me while shooting it, but it started working 100% again. I've never had to do that with any other gun ever but remembered some people swear by that trick when their gun is malfunctioning (this is the first time I've ever had a problem AR). I'm just going to get the FE upgrade before I start shooting again in the fall now that it's too hot.That seems inline with my thoughts about the crud entering the ejector spring channel. |
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Originally Posted By Alien: Took my RDB 9mm out again this past weekend. Started having failures to eject every single round right off the bat after not having any issues last time. Empty cases were stuck to the bolt! On a whim, I doused the bolt carrier and bolt/bolt face with CLP to get oil into the ejector channel. It blew nasty black oil all over me while shooting it, but it started working 100% again. I've never had to do that with any other gun ever but remembered some people swear by that trick when their gun is malfunctioning (this is the first time I've ever had a problem AR). I'm just going to get the FE upgrade before I start shooting again in the fall now that it's too hot.Funny you should mention that. I downloaded and read the RDB manual today and this is what it had to say about cleaning. Attached File But, it looks like this was written prior to the FE models. I got an FE Banshee delivered to my LGS today, and another. FE upper coming tomorrow. I've been busy swapping things around and trying to decide how I want to configure everything. As an aside, CMMG recommends buying their bolt weight kit to tune it for suppressor use. Any reason why changing buffer weight instead wouldn't work? |
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Originally Posted By Jambalaya: As an aside, CMMG recommends buying their bolt weight kit to tune it for suppressor use. Any reason why changing buffer weight instead wouldn't work? I used to run a .40SW bolt (60 degree) that I slotted for my custom fixed ejector which was required since the recoil impulse was so soft that a fixed ejector was required. I hope that they offer a retrofit kit for the .40SW in the future so I can try using that bolt in 9mm. I prefer to mechanically delay the action vs throwing mass at the problem. I have no idea if they will release a .40SW FE retrofit kit since that caliber isn't that popular and I haven't seen them post about it. I did see they posted on Reddit that a 10mm FE retrofit is coming. I would get that kit just to get that bolt for use in .40SW which is how I ran my .40SW before. I run .40SW occasionally because I still have plenty of brass for it and can sometimes get .40SW projectiles as cheap as 9mm for full auto blasting. Works great in SMG matches for knocking down steel plates. |
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Originally Posted By amphibian: That is what I prefer. I never liked adding more dead mass. IMHO, makes the gun more bouncy. Also as I posted in my picture above, remember that the new FE 9mm Banshee's are coming with a 55 degree bolt vs the spring loaded ejector Banshee's came with 50 degree bolts. So that should help with suppression. I used to run a .40SW bolt (60 degree) that I slotted for my custom fixed ejector which was required since the recoil impulse was so soft that a fixed ejector was required. I hope that they offer a retrofit kit for the .40SW in the future so I can try using that bolt in 9mm. I prefer to mechanically delay the action vs throwing mass at the problem. I have no idea if they will release a .40SW FE retrofit kit since that caliber isn't that popular and I haven't seen them post about it. I did see they posted on Reddit that a 10mm FE retrofit is coming. I would get that kit just to get that bolt for use in .40SW which is how I ran my .40SW before. I run .40SW occasionally because I still have plenty of brass for it and can sometimes get .40SW projectiles as cheap as 9mm for full auto blasting. Works great in SMG matches for knocking down steel plates. Yeah if there's ways to burn up .40 that's lying around, no reason not to. It's probably great in a PCC. I just never liked it in a handgun. I'm going to try to hit the range today or tomorrow with the FE and see how it runs. I've got to put some kind of ASR mount on it first though because I want to be quiet about it and not have a bunch of nosy folks show up at the range if they hear a FRT. I'll bring an H2 buffer to try. That's interesting about the 55 degree bolts too. One thing I'm unsure of with these FE bolts. With the bolt carrier out of the gun, you can see how rotating the bolt will force the carrier back as the bolt cams open. But then, what's to keep the bolt from trying to push itself back into the carrier as it continues to recoil once the lugs clear the barrel extension? It seems like the bolt would try to do this and consequently, the inside surface of the ejector slot would drag on the ejector as the bolt tries to rotate back as it pushes back into the carrier once the lugs clear the extension. The ejector would be the only thing stopping the rotation. I'm probably missing some physics or inertia effect that prevents this. But just fiddling with it, it seems like this would happen. |
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Originally Posted By Joker23: I am not an expert on ARs by any stretch of the imagination, but something I noticed that I wondered about. I have never changed an ejector spring before. When CMMG sent me new springs for the ejector and extractor (along with an extractor buffer), I had to pull the ejector spring out, it didn't fall out. The spring was so caked with crud, it looked like a pin more than a spring. With a regular DI AR, the gas comes through the gas tube and into the carrier key. Maybe the gas is directed different places/a different way than with the RDB system? Maybe all that crud finds its way into the ejector spring channel? Originally Posted By Joker23: Originally Posted By Jambalaya: I just went through the entire thread looking to see if there was a concensus on why the ejector springs were failing and there were a few theories ranging from blowback 9mm vs gas operated 5.46, headspace and extractor claw geometry. Did anyone ever prove what the problem was? I am not an expert on ARs by any stretch of the imagination, but something I noticed that I wondered about. I have never changed an ejector spring before. When CMMG sent me new springs for the ejector and extractor (along with an extractor buffer), I had to pull the ejector spring out, it didn't fall out. The spring was so caked with crud, it looked like a pin more than a spring. With a regular DI AR, the gas comes through the gas tube and into the carrier key. Maybe the gas is directed different places/a different way than with the RDB system? Maybe all that crud finds its way into the ejector spring channel? Clearly the issue is your gas tube. Post a pic of your gas tube and we'll be able to diagnose your issue. |
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Originally Posted By backbencher: Clearly the issue is your gas tube. Post a pic of your gas tube and we'll be able to diagnose your issue. I didn't phrase it very well. I was wondering if the difference between DI and blowback caused/allowed more crud to enter the ejector spring channel. |
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Originally Posted By Jambalaya: But then, what's to keep the bolt from trying to push itself back into the carrier as it continues to recoil once the lugs clear the barrel extension? |
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Okay, went to the range today with my 9mm FE Banshee. Recoil is definitely much milder than my blowback build. I was sighting in a PA micro prism with the Gemini 9mm reticle. For the entire range session I used a Magpul 17 round glock mag. I should have used a factory glock mag because that's what CMMG specifies. Anyhow I had one weird malfunction on the third mag, about halfway through it. The bolt wouldn't close, and there was a case turned 180 degrees stuck in the barrel extension with the case mouth facing rearward. It ran fine for the remainder of that magazine and 2 more. I had an H2 buffer with me, but it seemed to run fine without it. Also didn't have any of their bolt tuning weights installed. I honestly dont see any advantage to slowing it down as it seems to chug along at a nice moderate pace. Sitting at the bench, ejection was at about 4-5 o'clock and about 4-8 feet from the gun. All the cases looked sooty, but otherwise good. I was shooting TulAmmo brassmax 115gr FMJ. It will need a lot more rounds through it without a repeat of the flipped case before I can trust it, but hopefully that was just an aftermarket mag problem. It sure is fun to shoot though. This is also a bit of a Frankenstein gun. I bought a Banshee MkGs lower from the LGS and the only one they had was titanium cerakote. Looks like CMMG doesn't offer the FE uppers in Titanium so I got a tungsten upper. In the right light it doesn't look too stupid. |
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My fixed ejector kit finally got here. I was able to rebuild my upper with these parts. One note, that kinda made me a little aggravated, is the upper is not a standard shape/profile. So my midwest industries handguard did not want to fit. The tabs on it to make it line up with a standard upper, well the cmmg upper is solid in that area, causing the line up tabs to be in the way and prevent it from setting flush. So it irked my to have to trim those tabs off with a file to get the handguard to fit. Everything else went together ok. I am hoping to try it out this weekend, weather permitting. |
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Originally Posted By Joker23: I didn't phrase it very well. I was wondering if the difference between DI and blowback caused/allowed more crud to enter the ejector spring channel. Originally Posted By Joker23: Originally Posted By backbencher: Clearly the issue is your gas tube. Post a pic of your gas tube and we'll be able to diagnose your issue. I didn't phrase it very well. I was wondering if the difference between DI and blowback caused/allowed more crud to enter the ejector spring channel. I think it's the continuous pressure throughout extraction in a blowback or delayed blowback system that is crushing the spring. In a locked bolt gun, the case head is only pushing momentarily against the bolt face (ejector), then the case is being pulled rearward by the extractor. In a blowback or delayed blowback gun, the case head is pushing against the bolt face (CMMG's ejector) throughout the entire extraction period. This is why some straight blowback guns run just fine w/o extractors - the case is extracting itself as it runs the action open. |
I sell firearms produced by the finest child labor in the world, be it Filipino, Muslim, Mormon, Arizonan, or Texan.
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Originally Posted By Jeeps-And-Guns: My fixed ejector kit finally got here. I was able to rebuild my upper with these parts. One note, that kinda made me a little aggravated, is the upper is not a standard shape/profile. So my midwest industries handguard did not want to fit. The tabs on it to make it line up with a standard upper, well the cmmg upper is solid in that area, causing the line up tabs to be in the way and prevent it from setting flush. So it irked my to have to trim those tabs off with a file to get the handguard to fit. Everything else went together ok. I am hoping to try it out this weekend, weather permitting. Edit to add - I just looked up some installation videos of MI handguards. It looks like they have a new method of anti-rotation. I have the older gen that uses the arms that go on either side of the upper. I noticed that the new upper looked different and wondered if that would cause any issues with swapping the parts from my old upper. I use MI handguards too and have had some issues in the past with the tabs. I had one "milspec" upper that didn't even come close to fitting, and a second "milspec" upper that worked with no issues. Would you mind posting a picture of that area now that you got it installed? I'm probably going to have to do the same thing to mine. |
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Got to try out the fixed ejector kit today. I spent the first half of a mag getting my reflex sight zeroed back in, but no issues. It ejects about 4-5 o-clock. I had no issues related to the upper. I was trying out a diaryland defense frt and everything worked perfectly in semi auto, but in forced reset, I had a malfunction every so often. So I am writing that off to the trigger causing the issue, as it was perfect on semi auto. I put 100 rounds through it today. |
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Originally Posted By Jeeps-And-Guns: My fixed ejector kit finally got here. I was able to rebuild my upper with these parts. One note, that kinda made me a little aggravated, is the upper is not a standard shape/profile. So my midwest industries handguard did not want to fit. The tabs on it to make it line up with a standard upper, well the cmmg upper is solid in that area, causing the line up tabs to be in the way and prevent it from setting flush. So it irked my to have to trim those tabs off with a file to get the handguard to fit. Everything else went together ok. I am hoping to try it out this weekend, weather permitting.  |
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I got my Banshee FE upgrade kit installed and took it out this afternoon to test, and it is certainly an upgrade over the original Banshee. The ability to change springs and buffers is certainly a benefit over my Dissent, and I tried several springs (I sure wish I knew what all of them were) and it ran great all the way from a Tubb flat wire spring cut just short enough to make the buffer contact the retainer to what I think was a .308 carbine spring, and each one felt different. What I believe is the .308 Carbine spring is shorter than my normal carbine springs, and stiffer, but it allowed reliable function with my weak gamer loads and it soaked up the recoil of my full-power 9mm loads as well. It runs great with an SS equipped lower as well. |
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Originally Posted By amphibian: Yeah...like this... https://c3junkie.com/wp-content/uploads/2025/06/FEretro-kit-plus-barrel.jpg I just looked at the MI website again. I have a G3 handguard which has a part that connects at the bottom for anti rotation. I had issues with the part in red on another upper:  It looks like G4 got rid of the wings on the lower part and added anti rotation tabs at the top:  Looks like I'd have to modify my old one or a new one. Shame, I really like MI handguards. |
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Originally Posted By Joker23: I just looked at the MI website again. I have a G3 handguard which has a part that connects at the bottom for anti rotation. I had issues with the part in red on another upper: https://i.imgur.com/BOi1pFs.jpg It looks like G4 got rid of the wings on the lower part and added anti rotation tabs at the top: https://i.imgur.com/DiRfS8G.jpg Looks like I'd have to modify my old one or a new one. Shame, I really like MI handguards. I'd be inclined to lightly grind channels into the upper and also grind off part of the tabs/lugs on the inner surfaces so that there is still a mating, anti-rotation function between the two parts. MHO, YMMV, etc. |
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So looks like they are finally shit canning the old 9mm spring loaded ejector Banshee's. I was just looking at CMMG's site and no longer see the old spring loaded ejector Banshee complete uppers or firearms listed for 9mm. Looking at the spare parts page: https://cmmg.com/rdb-upper-parts They don't list the 9mm Banshee spring loaded ejector BCG either but do list it for 10mm, .40SW and 5.7. Interesting that they have two different .40SW BCG's depending on barrel length. I bet different bolt angles. |
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Originally Posted By texaspaulhouston: Can you please describe the recoil A lot less than a straight blowback. Hopefully even less once my A5 tube, Warthog Spring and Kynshot RB5007 are installed....if Neverwear will ever ship the damn spring. Right now mine is running with a standard carbine tube, spring and buffer, but is still pretty soft. Here's my son shooting it with the binary trigger if this gives you any indication: (The site won't properly imbed a youtube short video using the youtube tag above, so I just post the link) https://www.youtube.com/shorts/HHPArWDq8Uw |
| I shot my 5" and 8" FE 9mm uppers with the CMMG resolute lower this past weekend. They both functioned flawlessly. Also shot them with at least 8 different suppressors and every one worked great on both uppers. Very little POI change with all of them using tri lug. Zero issues and a great day at the range. I used Federal Syntech 150 gr and Glock 32 rounders and Magpul PMAG GL9 |
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First test with new tube, spring and buffer. It absolutely makes a difference. Even less felt recoil, but I wouldn't say it was a huge difference, but noticeable. Less is less. One thing that is also apparent is the cycle time of the action is noticeably slower. I like this set up a lot. This is going to be an absolute hoot once I get an FRT in it. The binary isn't bad, but requires a practiced finger to get consistent runs. With the new set up I've had adjust how I work the binary a little with the slower action. Now I just need to get some 300 Blk subs loaded up and see how that upper it runs on the lower and dial in the AGB. A big thanks to Amphibian again for turning me on to this set up. I really don't know why anyone would want to mess with straight blow back (except for maybe a super compact bufferless) with this available. |
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Originally Posted By EDL: First test with new tube, spring and buffer. It absolutely makes a difference. Even less felt recoil, but I wouldn't say it was a huge difference, but noticeable. Less is less. One thing that is also apparent is the cycle time of the action is noticeably slower. I like this set up a lot. This is going to be an absolute hoot once I get an FRT in it. Originally Posted By EDL: First test with new tube, spring and buffer. It absolutely makes a difference. Even less felt recoil, but I wouldn't say it was a huge difference, but noticeable. Less is less. One thing that is also apparent is the cycle time of the action is noticeably slower. I like this set up a lot. This is going to be an absolute hoot once I get an FRT in it. A big thanks to Amphibian again for turning me on to this set up. I really don't know why anyone would want to mess with straight blow back (except for maybe a super compact bufferless) with this available. I demonstrate that in this video:  Single - Double - UZI - MP5 - Phase2 The MP5 probably is one of the slowest cycling factory closed bolt SMG's and it is still a little too fast for my liking. Bear in mind, this isn't a knock on the MP5. It does what it was designed to do and I doing controlled 2 round bursts is easy but I want to do singles for competitions. I am not an operator or wanna be either. I am not kicking a door down with several guys all armed with MP5's to neutralize a target. I shoot these for fun in SMG matches where the ability to pull singles, doubles are highly valued due to various target arrays. All that said, I hope more people are using FRT's in this fashion in states that allow them in SMG matches and then hopefully, they become, 'common use'. Being able to pull off a single at will and have the ability to pull a two round burst into a target faster than what is humanly possible (Jerry Miculek was clocked at 300RPM with an AR15 and we are talking around 600RPM) with a standard semi trigger is something that can be proven and done in matches. Again, I have not seen this kind of control in other closed bolt FA platforms....even the MP5. Which is why I have such a love/hate relationship with CMMG. I love that finally we have a closed bolt setup that can be tuned to run this slow. I hate that it took them so long to fix the spring loaded ejector issues and even though they finally did that, they still do not offer different bolts with different angles for additional tuning. Which is why I built my PhaseII. I want less reciprocating mass and increased delay. The system has the potential to do more but I get that there are probably not that many people that want this level of tuning. |
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Originally Posted By amphibian: I can't even think of a bufferless straight blowback 9mm AR setup. I guess you are referring to something like a Scorpion outside of the AR family. The problem with all these bufferless designs is that IF you want to run them in full auto or FRT or whatever, they shoot too fast. Even the classical full size MP5 is a tad too fast. Yeah, I don't think any are "AR" exactly, but what I started looking at initially was this: https://www.bearcreekarsenal.com/9mm-5-parkerized-m49mm-5-parkerized-m4-barrel-1-10-twist-blow-back-4-sch-nrail-bufferless-pistol-1.html Of course any bufferless design has a completely different bolt/internals, but they are straight blow back. Would be interesting if the RDB system could be adapted to a bufferless design. Still wouldn't be as soft as an AR setup with the full buffer tube, but could certainly help mitigate that snap. |
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Originally Posted By EDL: Would be interesting if the RDB system could be adapted to a bufferless design. Still wouldn't be as soft as an AR setup with the full buffer tube, but could certainly help mitigate that snap.  DissentHybrid You can also find some threads with issues on the Dissent. I have seen where the recoil rods have broken making the gun inoperable. Also saw a thread where a customer was having issues with some typical Federal 9mm ammo and since the Dissent isn't tunable customer support just recommended lighter ammo. Both of which would be non-issues if leveraging the buffer tube. |
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Fair enough, I've never looked at the Dissent, so was unaware. Actually, until you pointed out the CMMG kit, I've never really paid a lot of attention to CMMG's stuff due to their price, just an awareness of their RDB system. Sounds like the Dissent has some promise with some engineering changes, but still most likely never be as soft as an AR set up. That aside, the bufferless guns with a short barrel and folding stock are VERY compact. |
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Originally Posted That aside, the bufferless guns with a short barrel and folding stock are VERY compact. I get the bufferless setups are compact and cool looking but other than being compact for transport I don't get it. Typically most folding stocks don't telescope. So they don't accommodate small frame shooters or body armor very well. So for actual shooting, the typical buffer tube is the most accommodating for various shooting conditions as well as leveraging all the current and future buffer and spring advancements. I'd rather just separate the upper from the lower if I need that compactness for transport and not give up the buffer tube. There is also the LAW folder as well as various kits like the DOLOs and the one where it folds between the upper and rail if that is your thing. Also by retaining the buffer tube and the components I am recommending, you can swap to 556 or 300BLk conventional uppers. |
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Sig makes 2 adjustable folding stocks. One has a fixed proprietary stock and another has a carbine buffer tube and you can use a stock or a brace. Jmac makes a skeletonized buffer tube folding stock too. Pricey. I have both of the Sig models. MCX https://www.sigsauer.com/mcx-mpx-folding-stock-adapter-6-position-low-profile-black.html Folding buffer adapter only |
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