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Posted: 4/30/2024 9:43:02 AM EDT
First of all, I know this is totally unnecessary and I'm doing this just for fun and academic purposes.
On that note, I don't think fluted chambers are even necessary on MP5's. One of my friends maintains the guns for a MG rental range and routinely swaps out MP5 barrels with cheap barrels he turns on his lathe and they are NOT fluted and work fine for blasting. I have no extraction or reliability issues with my full auto hybrid Dissent build I have posted about already and for those not familiar it is all on my website here: https://c3junkie.com/?page_id=1733 |
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IIRC, as far as MP5s go, a few years back an MG rental guy posted on a firearms website that they use (lower cost) unfluted barrels on their rental MP5s, BUT they use low power (and lower cost) ammo that doesn't swell and jam. Cheaper barrels AND cheaper ammo - a win-win!
MHO, YMMV, etc. |
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I predict it will work fine
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I'm cool with that! Although, you'll probably have tested it already by then.
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This may be enough that it could run with a Scheel buffer, or even a Maxim?
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Originally Posted By chevrofreak: This may be enough that it could run with a Scheel buffer, or even a Maxim? View Quote People are cheap (including me). I wouldn't pay someone to do this. I only did it since I have the means to do it myself. For most SMG's and MG's, I like a cyclic rate around 600 RPM. So in most cases, I am trying to slow the guns down but retain smoothness. If this setup works, and the expanding brass isn't fighting the extractor, I would anticipate an increase in the cyclic rate which I do not want but again just an experiment. The only configurations I have that I wouldn't mind making faster are an open bolt full size UZI and my FM9 belt fed upper. I have no idea what a fluted chamber would do in an open bolt gun. With the belt fed FM9, it was super slow running in the high 400's but since I dropped a Maxim RDB in it, I clocked it at 602RPM so just about perfect. Regarding the CMMG RDB, below is a 3 second video I did a long time ago troubleshooting all the ejector spring failures: This is with a factory Banshee barrel and bolt in there. Every RDB I've seen has this slop. That is what kills the ejector springs on the Banshee's which again isn't an issue with the Dissent since they now use a fixed ejector in the upper. Anyways, I would think that the brass would expand into the flutes during this little bit of straight rearward travel. 9mm CMMG RDB Headspacing |
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Originally Posted By amphibian: Anyways, I would think that the brass would expand into the flutes during this little bit of straight rearward travel. View Quote I thought the opposite in my prediction above as the purpose of the flutes is to equalize the pressure on the outside surface of the case, thus prevent it from sticking and ‘float’ the case out of the chamber. |
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Originally Posted By amphibian: I think it would work fine for those.....but just like I stated in my initial post I don't think any of this is needed even in an MP5. People are cheap (including me). I wouldn't pay someone to do this. I only did it since I have the means to do it myself. For most SMG's and MG's, I like a cyclic rate around 600 RPM. So in most cases, I am trying to slow the guns down but retain smoothness. If this setup works, and the expanding brass isn't fighting the extractor, I would anticipate an increase in the cyclic rate which I do not want but again just an experiment. The only configurations I have that I wouldn't mind making faster are an open bolt full size UZI and my FM9 belt fed upper. I have no idea what a fluted chamber would do in an open bolt gun. With the belt fed FM9, it was super slow running in the high 400's but since I dropped a Maxim RDB in it, I clocked it at 602RPM so just about perfect. Regarding the CMMG RDB, below is a 3 second video I did a long time ago troubleshooting all the ejector spring failures: This is with a factory Banshee barrel and bolt in there. Every RDB I've seen has this slop. That is what kills the ejector springs on the Banshee's which again isn't an issue with the Dissent since they now use a fixed ejector in the upper. Anyways, I would think that the brass would expand into the flutes during this little bit of straight rearward travel. https://www.youtube.com/watch?v=xhm4omLtW2s View Quote View All Quotes View All Quotes Originally Posted By amphibian: Originally Posted By chevrofreak: This may be enough that it could run with a Scheel buffer, or even a Maxim? People are cheap (including me). I wouldn't pay someone to do this. I only did it since I have the means to do it myself. For most SMG's and MG's, I like a cyclic rate around 600 RPM. So in most cases, I am trying to slow the guns down but retain smoothness. If this setup works, and the expanding brass isn't fighting the extractor, I would anticipate an increase in the cyclic rate which I do not want but again just an experiment. The only configurations I have that I wouldn't mind making faster are an open bolt full size UZI and my FM9 belt fed upper. I have no idea what a fluted chamber would do in an open bolt gun. With the belt fed FM9, it was super slow running in the high 400's but since I dropped a Maxim RDB in it, I clocked it at 602RPM so just about perfect. Regarding the CMMG RDB, below is a 3 second video I did a long time ago troubleshooting all the ejector spring failures: This is with a factory Banshee barrel and bolt in there. Every RDB I've seen has this slop. That is what kills the ejector springs on the Banshee's which again isn't an issue with the Dissent since they now use a fixed ejector in the upper. Anyways, I would think that the brass would expand into the flutes during this little bit of straight rearward travel. https://www.youtube.com/watch?v=xhm4omLtW2s That's interesting. The brass ejected from my CMMG 9mm is completely coated black with carbon. The only ammunition I have found that leaves normal unsooted brass is 124 grain NATO. |
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http://americanconservativeparty.org/
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Wow, I haven’t seen it deformed like that! I’m used to some light carbon lines like in your OP.
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Originally Posted By Wirebrush: That's interesting. The brass ejected from my CMMG 9mm is completely coated black with carbon. The only ammunition I have found that leaves normal unsooted brass is 124 grain NATO. View Quote |
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Additional details on my site: https://c3junkie.com/?page_id=2096 I am going to run it like this for a while. |
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FWIW, I run a Stribog, which is also roller delayed so same brass ectraction conditions as an MP5. Not only is the factory chamber not fluted, it's stepped. Runs fine with anything I feed it. I've never had any form of extraction or ejection failure in the 4000 rounds or so of mixed random ammo of every type. I'm not convinced flutting does much beyond a place for extreme fouling to go, in a roller delay
I also run a P7, which is a fluted chamber as well. I reload its brass all day long just fine. But then, the flute marks are only a little deformation, nothing like that photo. That brass life is different than an MP5, since it's a gas delayed blowback, and will start and have full movement under different timing and conditions than a roller delayed Mp5, and I suspect there is some.value to fluting a P7 - though I don't think Walther or Alien flute their gas delayed chambers - so maybe not. |
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Originally Posted By lazyengineer: FWIW, I run a Stribog, which is also roller delayed so same brass ectraction conditions as an MP5. Not only is the factory chamber not fluted, it's stepped. Runs fine with anything I feed it. I've never had any form of extraction or ejection failure in the 4000 rounds or so of mixed random ammo of every type. View Quote View All Quotes View All Quotes Originally Posted By lazyengineer: FWIW, I run a Stribog, which is also roller delayed so same brass ectraction conditions as an MP5. Not only is the factory chamber not fluted, it's stepped. Runs fine with anything I feed it. I've never had any form of extraction or ejection failure in the 4000 rounds or so of mixed random ammo of every type. As I originally posted, I did this experiment for educational / entertainment purposes not to address any shortcomings of the CMMG RDB system. Also, I have previously posted that my CMMG RDB configurations already extract on their own when suppressed with no suppressor mounted. They typically do require an extractor to be installed to extract with no suppressor mounted however but with this fluted chamber, they will extract with no extractor installed and no suppressor mounted which I think is impressive. I'm not convinced flutting does much beyond a place for extreme fouling to go, in a roller delay |
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Originally Posted By amphibian: I've got over 25K rounds through my previous CMMG RDB configuration w/ zero extraction issues either. As I originally posted, I did this experiment for educational / entertainment purposes not to address any shortcomings of the CMMG RDB system. Also, I have previously posted that my CMMG RDB configurations already extract on their own when suppressed with no suppressor mounted. They typically do require an extractor to be installed to extract with no suppressor mounted however but with this fluted chamber, they will extract with no extractor installed and no suppressor mounted which I think is impressive. It is my understanding that the purpose of a fluted chamber is for the gases to 'float' the fired round and has nothing to do with having a place for fouling to go. View Quote View All Quotes View All Quotes Originally Posted By amphibian: Originally Posted By lazyengineer: FWIW, I run a Stribog, which is also roller delayed so same brass ectraction conditions as an MP5. Not only is the factory chamber not fluted, it's stepped. Runs fine with anything I feed it. I've never had any form of extraction or ejection failure in the 4000 rounds or so of mixed random ammo of every type. As I originally posted, I did this experiment for educational / entertainment purposes not to address any shortcomings of the CMMG RDB system. Also, I have previously posted that my CMMG RDB configurations already extract on their own when suppressed with no suppressor mounted. They typically do require an extractor to be installed to extract with no suppressor mounted however but with this fluted chamber, they will extract with no extractor installed and no suppressor mounted which I think is impressive. I'm not convinced flutting does much beyond a place for extreme fouling to go, in a roller delay That's the theory. In a P7, which is gas-retarded blow-back, I think it actually might help. I know you can run a P7 without an extractor even, and it'll still run. But with a roller-delayed action, like MP5 or Stribog (and likely the CMMG RDB system as well) - I'm not sure it is necessary or does anything. The Stribog doesn't need it, and they even went with a stepped chamber, which can increase extraction requirements, and it runs fine. |
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Originally Posted By lazyengineer: But with a roller-delayed action, like MP5 or Stribog (and likely the CMMG RDB system as well) - I'm not sure it is necessary or does anything. The Stribog doesn't need it, and they even went with a stepped chamber, which can increase extraction requirements, and it runs fine. View Quote I also run about 99% full auto and suppressed with my CMMG RDB builds and have never broken an extractor in the past +25k rounds. |
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